Embedded systems security—an overview
Des Autom Embed Syst(2008)12:173–183
DOI10.1007/s10617-008-9027-x
Embedded systems security—an overview
Sri Parameswaran·Tilman Wolf
Received:16June2008/Accepted:25June2008/Published online:17July2008
?Springer Science+Business Media,LLC2008
Abstract Security is an important aspect of embedded system design.The characteristics of embedded systems give rise to a number of novel vulnerabilities.A variety of different solutions are being developed to address these security problems.In this paper,we provide a brief overview of important research topics in this domain.
Keywords Embedded system design·Vulnerabilities·Security
1Introduction
Security in embedded systems is a topic that has received an increasing amount of attention from industry and academia in recent years.Embedded systems are being deployed in a wide range of application areas ranging from control of safety-critical systems to data collection in hostile environments.These devices are inherently vulnerable to many operational problems and intentional attacks due to their embedded https://www.sodocs.net/doc/ae7282235.html,work connectivity opens even more avenues for remote exploits.In response,security solutions are being developed to provide robustness,protection from attacks,and recovery capabilities.
In this article,we provide an overview on embedded system security.We discuss how the characteristics of embedded systems lead to a set of potential vulnerabilities.We also provide a brief survey of attacks on embedded systems and corresponding countermeasures. For other overview articles on embedded system security,see[57,77].
S.Parameswaran
School of Computer Science and Engineering,University of New South Wales,Sydney,Australia
e-mail:sridevan@https://www.sodocs.net/doc/ae7282235.html,.au
T.Wolf( )
Department of Electrical and Computer Engineering,University of Massachusetts,Amherst,MA,USA
e-mail:wolf@https://www.sodocs.net/doc/ae7282235.html,
174S.Parameswaran,T.Wolf 2Characteristics and vulnerabilities of embedded systems
Many of the inherent characteristics of embedded systems have direct impact on security-related issues.We discuss some of their implications on vulnerabilities in embedded sys-tems.
2.1Characteristics
Embedded systems are used in special application domains where conventional workstation or server computers are not suitable due to functionality,cost,power requirements,size,or weight.The specialization of embedded system often comes with one or more drawbacks of the following type:
?Limited processing power implies that an embedded system typically cannot run appli-cations that are used for defenses against attacks in conventional computer systems(e.g., virus scanner,intrusion detection system).
?Limited available power is one of the key constraints in embedded systems.Many such systems operate on batteries and increased power consumption reduces system lifetime (or increases maintenance frequency).Therefore embedded system can dedicate only lim-ited power resources to providing system security.
?Physical exposure is typical of embedded systems that are deployed outside the imme-diate control of the owner or operator(e.g.,public location,customer premise).Thus, embedded systems are inherently vulnerable to attacks that exploit physical proximity of the attacker.
?Remoteness and unmanned operation is necessary for embedded system that are deployed in inaccessible locations(e.g.,harsh environment,remote?eld location).This limitation implies that deploying updates and patches as done with conventional workstations is dif?cult and has to be automated.Such automated mechanisms provide potential targets for attacks.
?Network connectivity via wireless or wired access is increasingly common for embedded systems.Such access is necessary for remote control,data collection,updates.In cases where the embedded system is connected to the Internet,vulnerabilities can be exploited remotely from anywhere.
These characteristics lead to a unique set of vulnerabilities that need to be considered in embedded systems.
2.2Vulnerabilities
Embedded system are vulnerable to a range of abuses that can aim at stealing private infor-mation,draining the power supply,destroying the system,or hijacking the system for other than its intended purpose.Examples of vulnerabilities in embedded systems are:?Energy drainage(exhaustion attack):Limited battery power in embedded systems makes them vulnerable to attacks that drain this resource.Energy drainage can be achieved by increasing the computational load,reducing sleep cycles,or increasing the use of sensors or other peripherals.
?Physical intrusion(tampering):The proximity of embedded systems to a potential at-tacker create vulnerabilities to attacks where physical access to the system is necessary. Examples are power analysis attacks or snooping attacks on the system bus.
Embedded systems security—an overview175?Network intrusion(malware attack):Networked embedded systems are vulnerable to the same type of remote exploits that are common for workstations and servers.An example is a buffer over?ow attacks.
?Information theft(privacy):Data stored on an embedded system is vulnerable to unau-thorized access since the embedded system may be deployed in a hostile environment. Example of data that should be protected are cryptographic keys or electronic currency on smart cards.
?Introduction of forged information(authenticity):Embedded systems are vulnerable to malicious introduction of incorrect data(either via the system’s sensors or by direct write to memory).Examples are wrong video feeds in security cameras or overwriting of mea-surement data in an electricity meter.
?Confusing/damaging of sensor or other peripherals:Similar to the introduction of mali-cious data,embedded systems are vulnerable to attacks that cause incorrect operation of sensors or peripherals.An examples is tampering with the calibration of a sensor.?Thermal event(thermal virus or cooling system failure):Embedded systems need to op-erate within reasonable environmental conditions.Due to the highly exposed operating environment of embedded systems,there is a potential vulnerability to attacks that over-heat the system(or cause other environmental damage).
?Reprogramming of systems for other purposes(stealing):While many embedded systems are general-purpose processing systems,they are often intended to be used for a particular use.These systems are vulnerable to unauthorized reprogramming for other uses.An example is the reprogramming of gaming consoles to run Linux.
In order to defend embedded systems from these attacks,it is necessary to consider dif-ferent types of attacks and countermeasures in more detail.
3Attacks and countermeasures
Security threats to embedded systems can be classi?ed by the objectives of the attacks or the means to launch the attack[76,77].As illustrated above,objectives of the attack can be to prevent privacy,overcome integrity or reduce availability.The means used to launch an attack can be either physical,logical or side channel based.Typical privacy attacks strike at authenticity,access control and con?dentiality.Logical attacks on the other hand can be either software based or cryptographic.
Examples of physical attacks include microprobing,reverse engineering and eavesdrop-ping.The resources available for reverse engineering increase signi?cantly if someone with manufacturing knowledge attempts to maliciously compromise the system.Integrated cir-cuits may be vulnerable to microprobing or analysis under an electron microscope,once acid or chemical means have been used to expose the bare silicon circuitry[70].Eavesdrop-ping is the intercepting of conversations by unintended recipients which are performed when sensitive information is passed via electronic media,such as e-mail or instant messaging.
Fault injection attacks[12,13],power analysis attacks[59](both Simple Power Analysis (SPA)and Differential Power Analysis(DPA)[54]),timing analysis attacks[15]and electro magnetic analysis attacks[75]are examples of side channel attacks.Side-channel attacks are performed based on observing properties of the system while it performs cryptographic operations.
176S.Parameswaran,T.Wolf 3.1Attacks on embedded systems
3.1.1Software attacks
Code injection attacks are examples of software attacks which today comprise the majority of all software attacks.The malicious code can be introduced remotely via the network.
Cryptographic attacks exploit the weakness in the cryptographic protocol information to perform security attacks,such as breaking into a system by guessing the password.A short list of common crypto and protocol vulnerabilities is given in[77].Solutions proposed in the literature to counter cryptographic attacks include run-time monitors that detect security policy violations[53]and the use of safe proof-carrying code[68].
Most of the recent security attacks result in demolishing code integrity of an application program[64].They include dynamically changing instructions with the intention of gain-ing control over a program execution?ow.Attacks that are involved in violating software integrity are called code injection attacks.Code injection attacks often exploit common im-plementation mistakes in application programs and are often called security vulnerabilities. The number of malicious attacks always increases with the amount of software code[18, 19].Some of the attacks include stack-based buffer over?ows,heap-based buffer over?ows, exploitation of double-free vulnerability,integer errors,and the exploitation of format string vulnerabilities.
3.1.2Side channel attacks
Side channel attacks are known for the ease with which they can be implemented,and for their effectiveness in stealing secret information from the device without leaving a trace [89].Adversaries observe side channels such as power usage[59],processing time[15] and electro magnetic(EM)emissions[71]while the chip is processing secure transactions. The adversary feeds different input values into the system,while recording the side channels during the execution of a cryptographic algorithm(e.g.,encryption using a secret key).These recorded external manifestations are then correlated with the internal computations.Side channel attacks can be performed successfully at either the sender or the receiver to identify the secret keys used for encryption and/or decryption.
Power dissipation/consumption of a chip is the most exploited property to determine secret keys using side channel attacks[56,89].Kocher et al.[54]?rst introduced power analysis attacks in1999,where secret keys used in an encryption program were successfully discovered by observing the power dissipation from a chip.Devices like Smart Cards[11, 22],PDAs[44]and Mobile Phones[88]have microprocessor chips built inside,performing secure transactions using secret keys.
3.2Countermeasures
3.2.1Countermeasures against software attacks
There are several countermeasures proposed in the literature to defend against code injec-tion attacks performed by exploiting common implementation vulnerabilities.These can be divided into nine groups based on:(1)the system component where the proposed counter-measure is implemented;and(2)the techniques used for the countermeasures.Following are the nine groups discussed here:
Embedded systems security—an overview177
1.Architecture based countermeasures
2.Safe languages
3.Static code analyzers
4.Dynamic code analyzers
5.Anomaly detection techniques
6.Sandboxing or damage containment approaches
https://www.sodocs.net/doc/ae7282235.html,piler support
8.Library support
9.Operating system based countermeasures
As return addresses of functions are the most attacked target of buffer over?ows,there are many hardware/architecture assisted countermeasures that aim to protect these addresses. Some of these techniques are described in[2,7,51,73].Another technique to counter code injection attack is to ensure code integrity at runtime.The authors in[72]have proposed a microarchitectural technique to ensure program code integrity at runtime and thereby pre-venting code injection attacks.An embedded monitoring system to check correct program execution is proposed in[60].
Safe languages such as Java and ML are capable of preventing some of the implementa-tion vulnerabilities discussed here.However,everyday programmers are using C and C++ to implement more and more low and high level applications and therefore the need for safe implementation of these languages exists.Safe dialects of C and C++use techniques such as restriction in memory management to prevent any implementation errors.Examples of such methods are shown in[25,32,35].
Static Code Analyzers,analyze software without actually executing programs built from that software[81].In most cases the analysis is performed on the source code and in the other cases on some form of the object code.The quality of the analysis performed by these tools ranges from those that only consider the behavior of simple statements and declarations,to those that include the complete source code of a program in their analysis.The information collected by these analyzers can be used in a range of applications,starting from detecting coding errors to formal methods that mathematically prove program properties.Examples of static code analyzers are shown in[3,17,26].
In dynamic code analysis,the source code is instrumented at compile time and then test runs are performed to detect vulnerabilities.Even though performing dynamic code analysis is more accurate than static analysis(more information of the execution is available at runtime compared to compile-time),dynamic code checking might miss some errors as they may not fall on the execution path while being analyzed.Some well known dynamic code analyzers are shown in[31,38,45].
Behavior-based anomaly detection compares a pro?le of all allowed application behavior to actual behavior of the application.Any deviation from the pro?le will raise a?ag as a potential security attack[48].This model is a positive security model as this model seeks only to identify all previously known good behaviors and decides that everything else is bad.Behavior anomaly detection has the potential to detect several type of attacks,which includes unknown and new attacks on an application code.Most of the time,the execution of system calls is monitored and is recorded as an anomaly if it does not correspond to one of the previously gathered patterns.A threshold value for the number of anomalies is decided a priori and when the threshold is reached,the anomaly can be reported to the system and subsequent action,such as terminating the program or declining a system call can be taken. On the negative side,behavior anomaly detection can lead to a high rate of false positives. For instance,if some changes are made to the application after a behavior pro?le is created,
178S.Parameswaran,T.Wolf behavior-based anomaly detection will wrongly identify access to these changes as potential attacks.Some examples of this technique are described in[40,50,82].
Sandboxing is a popular method for developing con?ned execution environments based on the principle of least privilege,which could be used to run untrusted programs.A sandbox limits or reduces the level of access its applications have to the system.Sandboxes have been of interest to systems researchers for a long time.Butler Lampson,in his1971paper [58],proposed a conceptual model highlighting properties of several existing protection and access-control enforcement mechanisms.Other examples are given in[36,37,53].
Compilers play a vital role in enabling the programs written via language speci?cations to run on hardware.The compiler is the most convenient place to insert a variety of solu-tions and countermeasures without changing the languages in which vulnerable programs are written.The observation that most of the security exploits are buffer over?ows and are caused by stack based buffers,has made researchers propose stack-frame protection mech-anisms.Protection of stack-frames is a countermeasure against stack based buffer over?ow attacks,where often the return address in the stack-frame is protected and some mechanisms are proposed to protect other useful information such as frame pointers.Another commonly proposed countermeasure is to protect program pointers in the code.This is a countermea-sure which is motivated by the fact that all code injection attacks need code pointers to be changed to point to the injected code.Since buffer over?ows are caused by writing data which is over the capacity of the buffers,it is possible to check the boundaries of the buffers when the data is written to prevent buffer over?ow attacks.Solutions proposed as compiler support for bounds checking are also discussed in this section.Some examples of the tech-niques are given in[4,14,16].
Safe library functions attempt to prevent vulnerabilities by proposing new string ma-nipulation functions which are less vulnerable or invulnerable to exploitations.In[65]the authors propose alternative string handling functions to the existing functions which assume strings are always NULL terminated.The new proposed functions also accept a size para-meter apart from the strings themselves.In[61],another safe string library is proposed as a replacement to the existing string library functions in C.Other examples are shown in[5, 10,27].
Operating system based solutions,use the observation that most attackers wish to execute their own code and have proposed solutions preventing the execution of such injected code. Most of the existing operating systems split the process memory into at least two segments, code and data.Marking the code segment read-only and the data segment non-executable will make it harder for an attacker to inject code into a running application and execute it [24,33,41].
3.2.2Countermeasures against side channel attacks
There are several countermeasures against side channel attacks.These have been divided into six categories:
1.Masking
2.Window method
3.Dummy instruction insertion
4.Code/algorithm modi?cation
5.Balancing
6.Other methods
To mask code execution and to confuse an adversary,noise can be injected during code execution.Examples of masking techniques are presented in[78,86,87].Substitution Boxes
Embedded systems security—an overview179 (SBOXes),often used in cryptology,can also be masked in the execution.Some examples for the SBOX masking techniques are presented in[28,42,46].
A window method can be applied in Public Key Cryptosystems to prevent power analysis based side channel attacks.In the window method,a modular exponentiation can be carried out by dividing the exponent into certain sizes of windows,and performing the exponentia-tion in iterations per window by randomly choosing the window[69].
Dummy instructions can be placed to provide random delays.This confuses the adversary when attempting to correlate the source implementation with the power pro?le.Chari et al.[20]claimed that countermeasures involving random delays(i.e.,dummy instructions used to provide random delays in an execution)should be performed extensively,otherwise they can be undone and re-ordered,causing a successful attack.Several dummy instruction approaches are presented in[1,6,43].
Public Key Cryptosystems like RSA and ECC have been severely attacked using Simple Power Analysis(SPA),mainly because of the conditional branching in the encryption.Such vulnerabilities in the program can be prevented by modifying the implementation or replac-ing with a better new algorithm to perform the same task.Key code modi?cation techniques to prevent power analysis are explained in[6,20,23].
The software code can be modi?ed in such a way that complementary events are coded to negate the effects of the actual computations.Examples of such code balancing techniques are presented in[21,29,79].Evidently,balancing at the gate level is the most appropriate solution to prevent power analysis,since the power is consumed/dissipated depending on the switching activities in gates.Hardware balancing is primarily performed by placing two gates in parallel,one complements the other when switching.Various hardware balancing techniques are given in[30,34,39].
Some of the other techniques include signal suppression circuits,which can be used to reduce the Signal-to-Noise Ratio(SNR)to prevent the adversary from differentiating the power pro?le.Examples for the suppression circuits are given in[52,67,74].Software level current balancing approaches are performed by modifying the source and inserting nop s to keep the current constant[66].
May et al.[62]proposed a non-deterministic processor design,where the independent in-structions are identi?ed and executed out-of-order in a random choice by the processor.This infringes the conventional attack rule removing the correlation between multiple executions of the same program,thus preventing the adversary from comparing different runs for power analysis.Several other improved versions of the non-deterministic processor architecture are proposed in[49,63].
Randomizing the clock signal[83]for the secure processor to confuse the adversary is another countermeasure proposed to prevent power analysis.This prevents the adversary from analyzing the clock signals to identify certain signi?cant instruction executions in the power pro?le.More examples on handling the clock signal to prevent power analysis are presented in[8,9,21,29,55].
Power analysis can also be prevented by designing special instructions whose power signature is dif?cult to analyze[46]or whose power consumption is data independent[80]. Several examples of creating extensible instructions are given in[39,47,84,85].Such extensible instruction designs can also be adapted to prevent power analysis attacks.
4Summary
In summary,embedded systems require special security considerations due to their inherent characteristics and unique usage scenarios.Research work in the?eld of embedded system
180S.Parameswaran,T.Wolf security is in the process of identifying attack scenarios,developing counter measures,and novel system designs with inherent security properties.
Acknowledgements We would like to thank Roshan Ragel,Angelo Ambrose and Jorgen Peddersen for their contributions in putting together this article.
References
1.Acii?mez O,Ko??K,Seifert J-P(2007)On the power of simple branch prediction analysis.In:ASI-
ACCS’07:proceedings of the2nd ACM symposium on information,computer and communications security.ACM,New York,pp312–320
2.Arora D,Ravi S,Raghunathan A,Jha NK(2005)Secure embedded processing through hardware-
assisted runtime monitoring.In:Proceedings of the design,automation and test in Europe(DATE’05), vol1
3.Ashcraft K,Engler D(2002)Using programmer-written compiler extensions to catch security holes.In:
SP’02:proceedings of the2002IEEE symposium on security and privacy.IEEE Computer Society, Washington,p143
4.Austin TM,Breach SE,Sohi GS(1994)Ef?cient detection of all pointer and array access errors.In:
PLDI’94:proceedings of the ACM SIGPLAN1994conference on programming language design and implementation.ACM,New York,pp290–301
5.Baratloo A,Singh N,Tsai T(2000)Transparent run-time defense against stack smashing attacks.In:
Proceedings of9th USENIX security symposium,June2000
6.Barbosa M,Page D(2005)On the automatic construction of indistinguishable operations.In:Cryptog-
raphy and coding.Lecture notes in computer science,vol3796.Springer,Berlin,pp233–247
7.Barrantes EG,Ackley DH,Palmer TS,Stefanovic D,Zovi DD(2003)Randomized instruction set emu-
lation to disrupt binary code injection attacks.In:CCS’03:proceedings of the10th ACM conference on computer and communications security.ACM,New York,pp281–289
8.Benini L,Macii A,Macii E,Omerbegovic E,Pro F,Poncino M(2003)Energy-aware design techniques
for differential power analysis protection.In:DAC’03:proceedings of the40th conference on design automation.ACM,New York,pp36–41
9.Benini L,Micheli GD,Macii E,Poncino M,Scarsi R(1999)Symbolic synthesis of clock-gating logic
for power optimization of synchronous controllers.ACM Trans Des Autom Electron Syst4(4):351–375 10.Bhatkar S,DuVarney DC,Sekar R(2003)Address obfuscation:an ef?cient approach to combat a broad
range of memory error exploits.In:12th USENIX security symposium,Washington,DC,August2003 11.Biham E,Shamir A(2003)Power analysis of the key scheduling of the AES candidates.In:Second
advanced encryption standard(AES)candidate conference,pp343–347
12.Boneh D,DeMillo RA,Lipton RJ(1997)On the importance of checking cryptographic protocols for
faults.In:Lecture notes in computer science,vol1233.Springer,Berlin,pp37–51
13.Boneh D,DeMillo RA,Lipton RJ(2001)On the importance of eliminating errors in cryptographic
computations.J Cryptol14(2):101–119
14.Bray B(2002)Compiler security checks in depth.Available at https://www.sodocs.net/doc/ae7282235.html,/tips/
seccheck.asp,February2002
15.Brumley D,Boneh D(2003)Remote timing attacks are practical.In:Proceedings of the12th USENIX
security symposium,August2003
16.Bulba and Kil3r(2000)Bypassing stackguard and stackshield.Phrack Mag10(56)
17.Bush WR,Pincus JD,Sielaff DJ(2000)A static analyzer for?nding dynamic programming errors.Softw
Pract Exp30(7):775–802
18.CERT Coordination Center(2004)Vulnerability notes database.CERT Coordination Center
19.CERT Coordination Center(2005)CERT/CC vulnerabilities statistics1988–2005.CERT Coordination
Center
20.Chari S,Jutla C,Rao JR,Rohatgi P(1999)A cautionary note regarding evaluation of AES candidates
on smart-cards.In:Second advanced encryption standard(AES)candidate conference,Rome,Italy.
https://www.sodocs.net/doc/ae7282235.html,/encryption/aes/round1/conf2/aes2conf.htm
21.Chari S,Jutla CS,Rao JR,Rohatgi P(1999)Towards sound approaches to counteract power-analysis
attacks.In:CRYPTO,pp398–412
22.Chaumette S,Sauveron D,New security problems raised by open multiapplication smart cards
23.Chevalier-Mames B,Ciet M,Joye M(2004)Low-cost solutions for preventing simple sidechannel analy-
sis:side-channel atomicity.IEEE Trans Comput53(6):760–768
Embedded systems security—an overview181 24.Chew M,Song D(2002)Mitigating buffer over?ows by operating system randomization.Technical Re-
port CMU-CS-02-197,Department of Computer Science,Carnegie Mellon University,December2002 25.Condit J,Harren M,McPeak S,Necula GC,Weimer W(2003)CCured in the real world.In:PLDI’03:
proceedings of the ACM SIGPLAN2003conference on programming language design and implemen-tation.ACM,New York,pp232–244
26.Cousot P,Halbwachs N(1978)Automatic discovery of linear restraints among variables of a program.In:
POPL’78:proceedings of the5th ACM SIGACT-SIGPLAN symposium on principles of programming languages.ACM,New York,pp84–96
27.Cowan C,Barringer M,Beattie S,Kroah-Hartman G,Frantzen M,Lokier J(2001)Formatguard:auto-
matic protection from printf format string vulnerabilities.In:Proceedings of the10th USENIX security https://www.sodocs.net/doc/ae7282235.html,ENIX Association,Berkeley,pp191–200
28.Daemen J,Peeters M,Assche GV(2001)Bitslice ciphers and power analysis attacks.In:FSE’00:
proceedings of the7th international workshop on fast software encryption.Springer,London,pp134–149
29.Daemen J,Rijmen V(1999)Resistance against implementation attacks:a comparative study of the AES
proposals.URL:https://www.sodocs.net/doc/ae7282235.html,/CryptoToolkit/aes/round1/pubcmnts.htm
30.Danil S,Julian M,Alexander B,Alex Y(2005)Design and analysis of dual-rail circuits for security
applications.IEEE Trans Comput54(4):449–460
31.Deeprasertkul P,Bhattarakosol P,O’Brien F(2005)Automatic detection and correction of programming
faults for software applications.J Syst Softw78(2):101–110
32.DeLine R,Fahndrich M(2001)Enforcing high-level protocols in low-level software.SIGPLAN Notes
36(5):59–69
33.Designer S(1997)Non-executable stack patch.Available at https://www.sodocs.net/doc/ae7282235.html,/events/sec02/
full_papers/lhee/lhee_html/node7.html
34.Dhem J-F,Feyt N(2001)Hardware and software symbiosis helps smart card evolution.IEEE Micro
21(6):14–25
35.Dhurjati D,Kowshik S,Adve V,Lattner C(2003)Memory safety without runtime checks or garbage
collection.In:LCTES’03:proceedings of the2003ACM SIGPLAN conference on language,compiler, and tool for embedded systems.ACM,New York,pp69–80
36.Erlingssonü,Schneider FB(2000)SASI enforcement of security policies:a retrospective.In:NSPW
’99:proceedings of the1999workshop on new security paradigms.ACM,New York,pp87–95
37.Evans D,Twyman A(1999)Flexible policy-directed code safety.In:IEEE symposium on security and
privacy,pp32–45
38.Fink G,Bishop M(1997)Property-based testing:a new approach to testing for assurance.SIGSOFT
Softw Eng Notes22(4):74–80
39.Fiskiran A,Lee R(2004)Evaluating instruction set extensions for fast arithmetic on binary?nite?elds.
In:Proceedings of the15th IEEE international conference on application-speci?c systems,architectures and processors,pp125–136
40.Forrest S,Hofmeyr SA,Somayaji A,Longstaff TA(1996)A sense of self for Unix processes.In:SP’96:
proceedings of the1996IEEE symposium on security and privacy.IEEE Computer Society,Washington, p120
41.Frantzen M,Shuey M(2001)StackGhost:hardware facilitated stack protection.In:10th USENIX secu-
rity symposium,pp55–66
42.Gebotys C(2006)A table masking countermeasure for low-energy secure embedded systems.IEEE
Trans Very Large Scale Integr Syst14(7):740–753
43.Gebotys CH,Gebotys RJ(2003)Secure elliptic curve implementations:an analysis of resistance to
power-attacks in a DSP processor.In:CHES’02:revised papers from the4th international workshop on cryptographic hardware and embedded systems.Springer,London,pp114–128
44.Gebotys CH,White BA(2006)Methodology for attack on a Java-based PDA.In:CODES+ISSS’06.
ACM,New York,pp94–99
45.Ghosh AK,O’Connor T(1998)Analyzing programs for vulnerability to buffer overrun attacks.In:Pro-
ceedings of the21st NIST-NCSC national information systems security conference,pp274–382
46.Goubin L,Patarin J(1999)Des and differential power analysis(the“duplication”method).In:CHES
’99:proceedings of the?rst international workshop on cryptographic hardware and embedded systems.
Springer,London,pp158–172
47.Gro?sch?dl J,Savas E(2004)Instruction set extensions for fast arithmetic in?nite?elds gf(p)and
gf(2m).In:CHES,pp133–147
48.Hofmeyr SA,Forrest S,Somayaji A(1998)Intrusion detection using sequences of system calls.J Com-
put Secur6(3):151–180
49.Irwin J,Page D,Smart NP(2002)Instruction stream mutation for non-deterministic processors.In:
ASAP’02:proceedings of the IEEE international conference on application-speci?c systems,architec-tures,and processors.IEEE Computer Society,Washington,p286
182S.Parameswaran,T.Wolf 50.Joglekar SP,Tate SR(2004)Protomon:embedded monitors for cryptographic protocol intrusion detec-
tion and prevention.In:Proceedings on the international conference on information technology:coding and computing(ITCC’04),vol1.IEEE Computer Society,Washington,p81
51.Kc GS,Keromytis AD,Prevelakis V(2003)Countering code-injection attacks with instruction-set ran-
domization.In:CCS’03:proceedings of the10th ACM conference on computer and communications security.ACM,New York,pp272–280
52.Kessels J,Kramer T,den Besten G,Peeters A,Timm V(2000)Applying asynchronous circuits in con-
tactless smart cards.In:Advanced research in asynchronous circuits and systems(ASYNC2000),pp36–44
53.Kiriansky V,Bruening D,Amarasinghe SP(2002)Secure execution via program shepherding.In:Pro-
ceedings of the11th USENIX security https://www.sodocs.net/doc/ae7282235.html,ENIX Association,Berkeley,pp191–206
54.Kocher P,Jaffe J,Jun B(1999)Differential power analysis.In:Lecture notes in computer science,
vol1666.Springer,Berlin,pp388–397
55.Kocher P,Jaffe J,Jun B(1999)Using unpredictable information to minimize leakage from smartcards
and other https://www.sodocs.net/doc/ae7282235.html, Patent6327661
56.Koeune F,Standaert F-X(2006)A tutorial on physical security and side-channel attacks.In:Foundations
of security analysis and design III:FOSAD2004/2005,pp78–108
57.Koopman P(2004)Embedded system https://www.sodocs.net/doc/ae7282235.html,puter37(7):95–97
https://www.sodocs.net/doc/ae7282235.html,mpson BW(1971)Protection.ACM Oper Syst8(1):18–24
59.Mangard S(2003)A simple power-analysis(SPA)attack on implementations of the AES key expansion.
In:Lee PJ,Lim CH(eds)Proceedings of the5th international conference on information security and cryptology(ICISC2002).Lecture notes in computer science,vol2587.Springer,Berlin,pp343–358 60.Mao S,Wolf T(2007)Hardware support for secure processing in embedded systems.In:Proceedings of
44th design automation conference(DAC),pp483–488,San Diego,CA,June2007
61.Messier M,Viega J(2005)Safe C string library.Available at https://www.sodocs.net/doc/ae7282235.html,/safestr/
62.May D,Muller HL,Smart NP(2001)Non-deterministic processors.In:ACISP’01:proceedings of the
6th Australasian conference on information security and privacy.Springer,London,pp115–129
63.May D,Muller HL,Smart NP(2001)Random register renaming to foil dpa.In:CHES’01:proceedings
of the third international workshop on cryptographic hardware and embedded systems.Springer,London, pp28–38
https://www.sodocs.net/doc/ae7282235.html,enkovic M,Milenkovic A,Jovanov E(2005)Hardware support for code integrity in embedded
processors.In:CASES’05:proceedings of the2005international conference on compilers,architec-tures and synthesis for embedded systems.ACM,New York,pp55–65
https://www.sodocs.net/doc/ae7282235.html,ler TC(1999)Strlcpy and strlcat—consistent,safe,string copy and concatenation.In:1999USENIX
annual technical https://www.sodocs.net/doc/ae7282235.html,ENIX Association,Monterey,pp175–178
66.Muresan R,Gebotys CH(2004)Current?attening in software and hardware for security applications.
In:CODES+ISSS,pp218–223
67.Muresan R,Vahedi H,Zhanrong Y,Gregori S(2005)Power-smart system-on-chip architecture for em-
bedded cryptosystems.In:CODES+ISSS’05:proceedings of the3rd IEEE/ACM/IFIP international con-ference on hardware/software codesign and system synthesis.ACM,New York,pp184–189
68.Necula GC(1997)Proof-carrying code.In:Conference record of POPL’97:the24th ACM SIGPLAN-
SIGACT symposium on principles of programming languages,Paris,France,January1997,pp106–119 69.Nedjah N,de Macedo Mourelle L,da Silva RM(2007)Ef?cient hardware for modular exponentiation
using the sliding-window method.In:ITNG’07:proceedings of the international conference on infor-mation technology.IEEE Computer Society,Washington,pp17–24
70.Wikipedia Foundation Inc.(2006)Pirate decryption de?nition.The free encyclopedia.http://en.
https://www.sodocs.net/doc/ae7282235.html,/wiki/Pirate_decryption
71.Quisquater J,Samyde D(2001)Electro magnetic analysis(EMA):measures and counter-measures for
smart cards.In:E-smart,pp200–210
72.Ragel RG,Parameswaran S(2006)IMPRES:integrated monitoring for processor reliability and security.
In:Proceedings of the design and automation conference2006(DAC’06).ACM,San Fransisco,pp502–505
73.Ragel RG,Parameswaran S,Kia SM(2005)Micro embedded monitoring for security in application
speci?c instruction-set processors.In:Proceedings of the international conference on compilers,archi-tectures,and synthesis for embedded systems(CASES’05).ACM,San Francisco
74.Rakers P,Connell L,Collins T,Russell D(2001)Secure contactless smartcard ASIC with DPA protec-
tion.IEEE J Solid-State Circuits,pp559–565
75.Rao JR,Rohatgi P(2001)Empowering side-channel attacks.Cryptology ePrint Archive,Report
2001/037
76.Ravi S,Raghunathan A,Chakradhar S(2004)Tamper resistance mechanisms for secure,embedded
systems.In:17th international conference on VLSI design,January2004
Embedded systems security—an overview183 77.Ravi S,Raghunathan A,Kocher P,Hattangady S(2004)Security in embedded systems:design chal-
lenges.Trans Embed Comput Syst3(3):461–491
78.Rostovtsev A,Shemyakina O(2005)AES side channel attack protection using random isomorphisms.
Cryptology ePrint Archive,Report2005/087
79.Sakai Y,Sakurai K(2006)Simple power analysis on fast modular reduction with generalized mersenne
prime for elliptic curve cryptosystems.IEICE Trans Fundam Electron Commun Comput Sci E89-A(1):231–237
80.Saputra H,Vijaykrishnan N,Kandemir M,Irwin MJ,Brooks R,Kim S,Zhang W(2003)Masking the
energy behavior of des encryption.01:10084
81.Wikipedia Foundation Inc.(2006)SCA de?nition.The free encyclopedia.https://www.sodocs.net/doc/ae7282235.html,/
wiki/Static_code_analysis
82.Sekar R,Bendre M,Dhurjati D,Bollineni P(2001)A fast automaton-based method for detecting anom-
alous program behaviors.In:SP’01:proceedings of the2001IEEE symposium on security and privacy.
IEEE Computer Society,Washington,p144
83.Sprunk E(1999)Clock frequency modulation for secure https://www.sodocs.net/doc/ae7282235.html, Patent WO99/63696
84.Tillich S,Gro?sch?dl J(2006)Instruction set extensions for ef?cient AES implementation on32-bit
processors.In:CHES,pp270–284
85.Tillich S,Gro?sch?dl J(2007)Power-analysis resistant AES implementation with instruction set exten-
sions.In:Paillier P,Verbauwhede I(eds)Proceedings of the9th international workshop on cryptographic hardware and embedded systems(CHES2007),Wienna,Austria,September10–13.Lecture notes in computer science,vol.4727.Springer,Berlin,pp303–319
86.Trichina E,Seta DD,Germani L(2003)Simpli?ed Adaptive Multiplicative Masking for AES.In:CHES
’02:revised papers from the4th international workshop on cryptographic hardware and embedded sys-tems.Springer,London,pp187–197
87.Wayner P(1998)Code breaker cracks smart cards’digital safe.In:New York Times,p C1
88.Wolf W(2005)Multimedia applications of multiprocessor systems-on-chips.In:DATE’05:proceedings
of the conference on design,automation and test in Europe.IEEE Computer Society,Washington,pp86–89
89.YongBin Zhou DF(2005)Side-channel attacks:ten years after its publication and the impacts on cryp-
tographic module security testing.Cryptology ePrint Archive,2005/388
中国姓氏英文翻译大全S-Z
A: 艾--Ai 安--Ann/An 敖--Ao B: 巴--Pa 白--Pai 包/鲍--Paul/Pao 班--Pan 贝--Pei 毕--Pih 卞--Bein 卜/薄--Po/Pu 步--Poo 百里--Pai-li C: 蔡/柴--Tsia/Choi/Tsai 曹/晁/巢--Chao/Chiao/Tsao 岑--Cheng 崔--Tsui 查--Cha 常--Chiong 车--Che 陈--Chen/Chan/Tan 成/程--Cheng 池--Chi 褚/楚--Chu 淳于--Chwen-yu D: 戴/代--Day/Tai 邓--Teng/Tang/Tung 狄--Ti 刁--Tiao 丁--Ting/T 董/东--Tung/Tong 窦--Tou 杜--To/Du/Too 段--Tuan 端木--Duan-mu 东郭--Tung-kuo 东方--Tung-fang E: F:
范/樊--Fan/Van 房/方--Fang 费--Fei 冯/凤/封--Fung/Fong 符/傅--Fu/Foo G: 盖--Kai 甘--Kan 高/郜--Gao/Kao 葛--Keh 耿--Keng 弓/宫/龚/恭--Kung 勾--Kou 古/谷/顾--Ku/Koo 桂--Kwei 管/关--Kuan/Kwan 郭/国--Kwok/Kuo 公孙--Kung-sun 公羊--Kung-yang 公冶--Kung-yeh 谷梁--Ku-liang H: 海--Hay 韩--Hon/Han 杭--Hang 郝--Hoa/Howe 何/贺--Ho 桓--Won 侯--Hou 洪--Hung 胡/扈--Hu/Hoo 花/华--Hua 宦--Huan 黄--Wong/Hwang 霍--Huo 皇甫--Hwang-fu 呼延--Hu-yen I: J: 纪/翼/季/吉/嵇/汲/籍/姬--Chi 居--Chu 贾--Chia 翦/简--Jen/Jane/Chieh 蒋/姜/江/--Chiang/Kwong 焦--Chiao 金/靳--Jin/King 景/荆--King/Ching
图像处理中值滤波器中英文对照外文翻译文献
中英文资料对照外文翻译 一、英文原文 A NEW CONTENT BASED MEDIAN FILTER ABSTRACT In this paper the hardware implementation of a contentbased median filter suitabl e for real-time impulse noise suppression is presented. The function of the proposed ci rcuitry is adaptive; it detects the existence of impulse noise in an image neighborhood and applies the median filter operator only when necessary. In this way, the blurring o f the imagein process is avoided and the integrity of edge and detail information is pre served. The proposed digital hardware structure is capable of processing gray-scale im ages of 8-bit resolution and is fully pipelined, whereas parallel processing is used to m inimize computational time. The architecturepresented was implemented in FPGA an d it can be used in industrial imaging applications, where fast processing is of the utm ost importance. The typical system clock frequency is 55 MHz. 1. INTRODUCTION Two applications of great importance in the area of image processing are noise filtering and image enhancement [1].These tasks are an essential part of any image pro cessor,whether the final image is utilized for visual interpretation or for automatic an alysis. The aim of noise filtering is to eliminate noise and its effects on the original im age, while corrupting the image as little as possible. To this end, nonlinear techniques (like the median and, in general, order statistics filters) have been found to provide mo re satisfactory results in comparison to linear methods. Impulse noise exists in many p ractical applications and can be generated by various sources, including a number of man made phenomena, such as unprotected switches, industrial machines and car ign ition systems. Images are often corrupted by impulse noise due to a noisy sensor or ch annel transmission errors. The most common method used for impulse noise suppressi on n forgray-scale and color images is the median filter (MF) [2].The basic drawback o f the application of the MF is the blurringof the image in process. In the general case,t he filter is applied uniformly across an image, modifying pixels that arenot contamina ted by noise. In this way, the effective elimination of impulse noise is often at the exp ense of an overalldegradation of the image and blurred or distorted features[3].In this paper an intelligent hardware structure of a content based median filter (CBMF) suita ble for impulse noise suppression is presented. The function of the proposed circuit is to detect the existence of noise in the image window and apply the corresponding MF
中国姓氏英语翻译大全
中国姓氏英语翻译大全 A: 艾--Ai 安--Ann/An 敖--Ao B: 巴--Pa 白--Pai 包/鲍--Paul/Pao 班--Pan 贝--Pei 毕--Pih 卞--Bein 卜/薄--Po/Pu 步--Poo 百里--Pai-li C: 蔡/柴--Tsia/Choi/Tsai 曹/晁/巢--Chao/Chiao/Tsao 岑--Cheng 崔--Tsui 查--Cha
常--Chiong 车--Che 陈--Chen/Chan/Tan 成/程--Cheng 池--Chi 褚/楚--Chu 淳于--Chwen-yu D: 戴/代--Day/Tai 邓--Teng/Tang/Tung 狄--Ti 刁--Tiao 丁--Ting/T 董/东--Tung/Tong 窦--Tou 杜--To/Du/Too 段--Tuan 端木--Duan-mu 东郭--Tung-kuo 东方--Tung-fang E: F:
范/樊--Fan/Van 房/方--Fang 费--Fei 冯/凤/封--Fung/Fong 符/傅--Fu/Foo G: 盖--Kai 甘--Kan 高/郜--Gao/Kao 葛--Keh 耿--Keng 弓/宫/龚/恭--Kung 勾--Kou 古/谷/顾--Ku/Koo 桂--Kwei 管/关--Kuan/Kwan 郭/国--Kwok/Kuo 公孙--Kung-sun 公羊--Kung-yang 公冶--Kung-yeh 谷梁--Ku-liang H:
韩--Hon/Han 杭--Hang 郝--Hoa/Howe 何/贺--Ho 桓--Won 侯--Hou 洪--Hung 胡/扈--Hu/Hoo 花/华--Hua 宦--Huan 黄--Wong/Hwang 霍--Huo 皇甫--Hwang-fu 呼延--Hu-yen I: J: 纪/翼/季/吉/嵇/汲/籍/姬--Chi 居--Chu 贾--Chia 翦/简--Jen/Jane/Chieh 蒋/姜/江/--Chiang/Kwong
图像处理外文翻译 (2)
附录一英文原文 Illustrator software and Photoshop software difference Photoshop and Illustrator is by Adobe product of our company, but as everyone more familiar Photoshop software, set scanning images, editing modification, image production, advertising creative, image input and output in one of the image processing software, favored by the vast number of graphic design personnel and computer art lovers alike. Photoshop expertise in image processing, and not graphics creation. Its application field, also very extensive, images, graphics, text, video, publishing various aspects have involved. Look from the function, Photoshop can be divided into image editing, image synthesis, school tonal color and special effects production parts. Image editing is image processing based on the image, can do all kinds of transform such as amplifier, reducing, rotation, lean, mirror, clairvoyant, etc. Also can copy, remove stain, repair damaged image, to modify etc. This in wedding photography, portrait processing production is very useful, and remove the part of the portrait, not satisfied with beautification processing, get let a person very satisfactory results. Image synthesis is will a few image through layer operation, tools application of intact, transmit definite synthesis of meaning images, which is a sure way of fine arts design. Photoshop provide drawing tools let foreign image and creative good fusion, the synthesis of possible make the image is perfect. School colour in photoshop with power is one of the functions of deep, the image can be quickly on the color rendition, color slants adjustment and correction, also can be in different colors to switch to meet in different areas such as web image design, printing and multimedia application. Special effects production in photoshop mainly by filter, passage of comprehensive application tools and finish. Including image effects of creative and special effects words such as paintings, making relief, gypsum paintings, drawings, etc commonly used traditional arts skills can be completed by photoshop effects. And all sorts of effects of production are
双语：中国姓氏英文翻译对照大合集
[ ]
步Poo 百里Pai-li C: 蔡/柴Tsia/Choi/Tsai 曹/晁/巢Chao/Chiao/Tsao 岑Cheng 崔Tsui 查Cha 常Chiong 车Che 陈Chen/Chan/Tan 成/程Cheng 池Chi 褚/楚Chu 淳于Chwen-yu
D: 戴/代Day/Tai 邓Teng/Tang/Tung 狄Ti 刁Tiao 丁Ting/T 董/东Tung/Tong 窦Tou 杜To/Du/Too 段Tuan 端木Duan-mu 东郭Tung-kuo 东方Tung-fang F: 范/樊Fan/Van
房/方Fang 费Fei 冯/凤/封Fung/Fong 符/傅Fu/Foo G: 盖Kai 甘Kan 高/郜Gao/Kao 葛Keh 耿Keng 弓/宫/龚/恭Kung 勾Kou 古/谷/顾Ku/Koo 桂Kwei 管/关Kuan/Kwan
郭/国Kwok/Kuo 公孙Kung-sun 公羊Kung-yang 公冶Kung-yeh 谷梁Ku-liang H: 海Hay 韩Hon/Han 杭Hang 郝Hoa/Howe 何/贺Ho 桓Won 侯Hou 洪Hung 胡/扈Hu/Hoo
花/华Hua 宦Huan 黄Wong/Hwang 霍Huo 皇甫Hwang-fu 呼延Hu-yen J: 纪/翼/季/吉/嵇/汲/籍/姬Chi 居Chu 贾Chia 翦/简Jen/Jane/Chieh 蒋/姜/江/ Chiang/Kwong 焦Chiao 金/靳Jin/King 景/荆King/Ching
图像处理中常用英文词解释
Algebraic operation 代数运算一种图像处理运算，包括两幅图像对应像素的和、差、积、商。 Aliasing 走样（混叠）当图像像素间距和图像细节相比太大时产生的一种人工痕迹。Arc 弧图的一部分；表示一曲线一段的相连的像素集合。 Binary image 二值图像只有两级灰度的数字图像（通常为0和1，黑和白） Blur 模糊由于散焦、低通滤波、摄像机运动等引起的图像清晰度的下降。 Border 边框一副图像的首、末行或列。 Boundary chain code 边界链码定义一个物体边界的方向序列。 Boundary pixel 边界像素至少和一个背景像素相邻接的内部像素（比较：外部像素、内部像素） Boundary tracking 边界跟踪一种图像分割技术，通过沿弧从一个像素顺序探索到下一个像素将弧检测出。 Brightness 亮度和图像一个点相关的值，表示从该点的物体发射或放射的光的量。 Change detection 变化检测通过相减等操作将两幅匹准图像的像素加以比较从而检测出其中物体差别的技术。 Class 类见模或类 Closed curve 封闭曲线一条首尾点处于同一位置的曲线。 Cluster 聚类、集群在空间（如在特征空间）中位置接近的点的集合。 Cluster analysis 聚类分析在空间中对聚类的检测，度量和描述。 Concave 凹的物体是凹的是指至少存在两个物体内部的点，其连线不能完全包含在物体内部（反义词为凸） Connected 连通的 Contour encoding 轮廓编码对具有均匀灰度的区域，只将其边界进行编码的一种图像压缩技术。 Contrast 对比度物体平均亮度（或灰度）与其周围背景的差别程度 Contrast stretch 对比度扩展一种线性的灰度变换 Convex 凸的物体是凸的是指连接物体内部任意两点的直线均落在物体内部。Convolution 卷积一种将两个函数组合成第三个函数的运算，卷积刻画了线性移不变系统的运算。 Corrvolution kernel 卷积核1，用于数字图像卷积滤波的二维数字阵列，2，与图像或信号卷积的函数。 Curve 曲线1，空间的一条连续路径，2 表示一路径的像素集合（见弧、封闭曲线）。 Deblurring 去模糊1一种降低图像模糊，锐化图像细节的运算。2 消除或降低图像的模糊，通常是图像复原或重构的一个步骤。 Decision rule 决策规则在模式识别中，用以将图像中物体赋以一定量的规则或算法，这种赋值是以对物体特征度量为基础的。 Digital image 数字图像 1 表示景物图像的整数阵列，2 一个二维或更高维的采样并量化的函数，它由相同维数的连续图像产生，3 在矩形（或其他）网络上采样一连续函数，并才采样点上将值量化后的阵列。 Digital image processing 数字图像处理对图像的数字化处理；由计算机对图片信息进
连接座加工工艺规程编制说明书
机械制造学 课程设计说明书 题目名称连接座加工工艺规程编制专业班级11级机械制造及自动化2班学生姓名 学号 指导教师王月英 机械与电子工程系 二○一四年六月二十日
目录 任务书----------------------------------------------------------------------------------------------3 指导教师评阅表----------------------------------------------------------------------------------4 一、序言----------------------------------------------------------------------------------------8 二、零件的分析--------------------------------------------------------------------------------9 三、工艺规程的设计----------------------------------------------------------------------------10 （1）. 确定毛坯的制造形式----------------------------------------------------------------12 （2）. 基面的选择-----------------------------------------------------------------------------15 （3）. 制订工艺路线--------------------------------------------------------------------------17 （4）. 机械加工余量、工序尺寸及毛坯尺寸的确--------------------------------------19 （5）. 确定切削用量及基本工时-----------------------------------------------------------20 四、设计心得与小结-----------------------------------------------------------------------------23 五、参考文献-------------------------------------------------------------------------------------23
中国姓氏英语翻译大全
中国姓氏英语翻译大全 A: 艾--Ai 安--Ann/An 敖--Ao B: 巴--Pa 白--Pai 包/鲍--Paul/Pao 班--Pan 贝--Pei 毕--Pih 卞--Bein 卜/薄--Po/Pu 步--Poo 百里--Pai-li C: 蔡/柴--Tsia/Choi/Tsai 曹/晁/巢--Chao/Chiao/Tsao 岑--Cheng 崔--Tsui 查--Cha 常--Chiong 车--Che 陈--Chen/Chan/Tan 成/程--Cheng 池--Chi 褚/楚--Chu 淳于--Chwen-yu D: 戴/代--Day/Tai 邓--Teng/Tang/Tung 狄--Ti 刁--Tiao 丁--Ting/T 董/东--Tung/Tong 窦--Tou 杜--To/Du/Too 段--Tuan 端木--Duan-mu 东郭--Tung-kuo 东方--Tung-fang E: F: 范/樊--Fan/Van 房/方--Fang 费--Fei 冯/凤/封--Fung/Fong 符/傅--Fu/Foo G: 盖--Kai 甘--Kan 高/郜--Gao/Kao 葛--Keh 耿--Keng 弓/宫/龚/恭--Kung 勾--Kou 古/谷/顾--Ku/Koo 桂--Kwei 管/关--Kuan/Kwan 郭/国--Kwok/Kuo 公孙--Kung-sun 公羊--Kung-yang 公冶--Kung-yeh 谷梁--Ku-liang H: 海--Hay 韩--Hon/Han 杭--Hang 郝--Hoa/Howe 何/贺--Ho 桓--Won 侯--Hou 洪--Hung 胡/扈--Hu/Hoo 花/华--Hua 宦--Huan 黄--Wong/Hwang 霍--Huo 皇甫--Hwang-fu 呼延--Hu-yen I: J: 纪/翼/季/吉/嵇/汲/籍/姬--Chi
机械加工工艺编制阶梯轴加工工艺路线拟定
机械加工工艺编制（阶梯轴加工工艺路线拟定） 系部：机械工程系教师：张春明 授课班级：大专机制专业科目：机械加工工艺编制 时间：2013年4月12日地点：306（1） 一、课题名称：阶梯轴加工工艺路线拟定 二、教学目标： 1、知识技能目标：复习轴类零件的材料、热处理及机械加工方法，学习轴的机 械加工、热处理和辅助工序的安排，理解何时安排热处理工序和辅助工序，并能正确安排阶梯轴加工工艺路线。 2、过程与方法：教师通过多种不同加工路线的讲解，学习正确合理安排机械加 工工艺路线，并掌握科学安排机械加工工艺路线的基本方法。 3、情感态度与价值观：通过学习让学生理解一个机器零件的加工要许多工序在 不同的车间才能完成，从而培养学生干工作做事情不能投机取巧，要脚踏实地团结合作，才能把事情做好。 三、教学重点：理解加工分段进行，以主要加工表面为主线，次要表面穿插其中。 教学难点：热处理工序的安排。 四、教学准备：挂图。 五、教学过程设计： （一）导入 1、简约板书上节课主要内容。 2、上节课我们讲了轴类零件的材料和热处理工艺，不同的材料热处理工艺也是有所不同。本节课我们来看一看这样一个轴类零件怎样来进行加工，如何安排它的加工工艺路线。出示挂图。 （二）教学新课 1、出示问题：（1）零件材料是什么？主要加工表面是那个？ （2）进行什么热处理？机械加工工序的安排？ 小组讨论。 2、指名回答问题： 图中零件材料是什么？根据学生回答指出。并根据零件材料说明应进行何种热处理。 图中零件主要加工表面是那个？根据学生回答指出并讲解，让学生直观感知和
加深理解。 根据零件主要加工表面的技术要求，详细讲解零件所要进行的机械加工工序，再进行分析、比较。 根据机械加工工序，合理安排热处理工序，再安排辅助工序。小组讨论，最后确定该零件加工工艺路线。 3、小结： 1）机器零件加工工艺路线，应合理科学的安排。只有这样才能保证机器零件的加工质量。 2）机器零件加工工艺路线，包含机械加工，热处理工序和辅助加工工序。各工序都是穿插进行的，应根据零件的材料、技术要求妥善安排，机器零件加工工艺路线也不是唯一的。
图像处理英文翻译
数字图像处理英文翻译 （Matlab帮助信息简介） xxxxxxxxx xxx Introduction MATLAB is a high-level technical computing language and interactive environment for algorithm development, data visualization, data analysis, and numeric computation. Using the MATLAB product, you can solve technical computing problems faster than with traditional programming languages, such as C, C++, and Fortran. You can use MATLAB in a wide range of applications, including signal and image processing, communications, control design, test and measurement, financial modeling and analysis, and computational biology. Add-on toolboxes (collections of special-purpose MATLAB functions, available separately) extend the MATLAB environment to solve particular classes of problems in these application areas. The MATLAB system consists of these main parts: Desktop Tools and Development Environment This part of MATLAB is the set of tools and facilities that help you use and become more productive with MATLAB functions and files. Many of these tools are graphical user interfaces. It includes: the
工艺设计规范流程的编制
工艺规程的编制 在生产过程中，按本单位的实际情况，根据设计技术要求，需制订必要的工艺规程，以利于安排生产。零件加工的工艺规程就是一系列不同工序的综合。由于生产规模与具体情况的不同，对于同一零件的加工工序可能有很多方案，应当根据具体条件，采用其中最完善（从工艺上来说）和最经济的一个方案。 1.影响编制工艺规程的因素 a)生产规模是决定生产类型（单件、成批、大量）的主要因素，也是设备、 工夹量具、机械化与自动化程度等的选择。 b)制造零件所用到坯料或型材的形状、尺寸和精度是选择加工总余量和加 工过程中头几道工序的决定因素。 c)零件材料的性质（硬度、可加工性、热处理在工艺路线中排列的先后等） 是决定热处理工序和选用设备及切削用量的依据。 d)零件制造的精度，包括尺寸公差、形位公差以及零件图上所指定或技术 条件中所补充指定的要求。 e)零件的表面粗糙度是决定表面上光精加工工序的类别和次数的主要因素。 f)特殊的限制条件，例如工厂的设备和用具的条件等。 g)编制的加工规程要在既定生产规程与生产条件下达到多、快、好、省的 生产效果。 2.工艺规程的编制步骤 工艺规程的编制，可按下列步骤进行：
a)研究零件图及技术条件。如零件复杂、要求高，要先详细熟悉在机器中 所起的作用、加工材料及热处理方法、毛坯的类别与尺寸，并分析对零件制造精度的要求，然后选择毛基面，再选择零件重要表面加工所需的光基面。 b)加工的毛基面和光基面确定后，最初工序（由毛基面所决定的）和主要 表面的粗、精加工工序（在某种程度上由光基面决定）已很荆楚，也就能编制零件加工的顺序。 c)分析已加工表面的粗糙度，在已拟的加工顺序中增添光精加工的工序。 d)根据加工时的便利情况，确定并排列零件上下不重要表面加工所需的所 有其余工序（带自由尺寸的表面的加工、减小零件质量的工序、改善外观的工序、不重要的螺纹切削等）。这一类次要工序往往分配在已设计了的主要工序之间（或与之合并），也有时放在加工过程的末尾。这时必须考虑到，由于次要工序排列不当，在执行中会有损坏精密加工后的重要表面的可能性。 e)如果有限制加工工艺规程选择的特殊条件存在，通常要作补充说明，以 修正加工的顺序。 f)确定每一工序所需的机床和工具，填写工艺卡和工序卡。 g)详细拟定工艺规程时，必须进行全部加工时间的标定和单件加工时间的 结算，并计算每一工序所需的机床台数。但有时把已拟订好的工艺规程作某些修正（例如个别机床任务太少，则有必要把几个单独工序合并成一个工序）。
中国姓氏英文翻译大全
中国姓氏英文翻译大全 A: 艾--Ai 安--Ann/An 敖--Ao B: 巴--Pa 白--Pai 包/鲍--Paul/Pao 班--Pan 贝--Pei 毕--Pih 卞--Bein 卜/薄--Po/Pu 步--Poo 百里--Pai-li C: 蔡/柴--Tsia/Choi/Tsai 曹/晁/巢--Chao/Chiao/Tsao 岑--Cheng 崔--Tsui 查--Cha 常--Chiong 车--Che 陈--Chen/Chan/Tan 成/程--Cheng 池--Chi 褚/楚--Chu 淳于--Chwen-yu D: 戴/代--Day/Tai 邓--Teng/Tang/Tung 狄--Ti 刁--Tiao 丁 --Ting/T 董/东--Tung/Tong 窦--Tou 杜--To/Du/Too 段--Tuan 端木--Duan-mu 东郭--Tung-kuo 东方--Tung-fang E: F: 范/樊--Fan/Van 房/方--Fang 费--Fei 冯/凤/封--Fung/Fong 符/傅 --Fu/Foo G: 盖--Kai 甘--Kan 高/郜--Gao/Kao 葛--Keh 耿--Keng 弓/宫/龚/恭--Kung 勾--Kou 古/谷/顾--Ku/Koo 桂--Kwei 管/关--Kuan/Kwan 郭/国--Kwok/Kuo 公孙--Kung-sun 公羊 --Kung-yang 公冶--Kung-yeh 谷梁--Ku-liang H: 海--Hay 韩--Hon/Han 杭--Hang 郝--Hoa/Howe 何/贺--Ho 桓--Won 侯--Hou 洪--Hung 胡/扈--Hu/Hoo 花/华--Hua 宦--Huan 黄--Wong/Hwang 霍--Huo 皇甫--Hwang-fu 呼延--Hu-yen I: J: 纪/翼/季/吉/嵇/汲/籍/姬--Chi 居--Chu 贾--Chia 翦/简 --Jen/Jane/Chieh 蒋/姜/江/--Chiang/Kwong 焦--Chiao 金/靳--Jin/King 景/荆 --King/Ching 讦--Gan K: 阚--Kan 康--Kang 柯--Kor/Ko 孔--Kong/Kung 寇--Ker 蒯--Kuai 匡--Kuang L: 赖--Lai 蓝--Lan 郎--Long 劳--Lao 乐--Loh 雷--Rae/Ray/Lei 冷--Leng 黎/郦/利/李--Lee/Li/Lai/Li 连--Lien 廖--Liu/Liao 梁--Leung/Liang 林/蔺--Lim/Lin
零件加工工艺的编制
零件加工工艺的编制 课程作业 班级: 数控1班 姓名: 学号: 前言 机械制造工艺学课程设计，是以切削理论为基础、制造工艺为主线、兼顾工
艺装备知识的机械制造技术基本能力的培养；是综合运用机械制造技术的基本知识、基本理论和基本技能，分析和解决实际工程问题的一个重要教学环节；是对学生运用所掌握的“机械制造技术基础”知识及相关知识的一次全面训练。 机械制造技术基础课程设计，是以机械制造工艺及工艺装备为内容进行的设计。即以所选择的一个中等复杂程度的中小型机械零件为对象，编制其机械加工工艺规程，并对其中某一工序进行机床专用夹具设计。 机械制造工艺学课程设计是作为未来从事机械制造技术工作的一次基本训练。通过课程设计培养学生制定零件机械加工工艺规程和分析工艺问题的能力，以及设计机床夹具的能力。在设计过程中，我熟悉了有关标准和设计资料，学会使用有关手册和数据库。 1、能熟练运用机械制造工艺学课程中的基本理论以及在生产实践中学到的实践知识，正确地解决一个零件在加工中的定位、夹紧以及工艺路线安排、工艺尺寸确定等问题，保证零件的加工质量。 2、提高结构设计能力。学生通过夹具设计的训练，应获得根据被加工零件的加工要求，设计出高效、省力、经济合理而能保证加工质量的夹具的能力。 3、学会使用手册、图表及数据库资料。掌握与本设计有关的各种资料的名称、出处，能够做到熟练运用。 就我个人而言，我希望能通过这次课程设计锻炼自己分析问题、解决问题的能力，为今后所从事的工作打下基础。 由于本人能力有限，设计尚有许多不足之处，可请各位老师给予批评指正。 目录 前言 (1) 零件的工艺分析 (4)
中国姓氏英文翻译大全
中国姓氏英文翻译大全 A: 艾--Ai 安--Ann/An 敖--Ao B: 巴--Pa 白--Pai 包/鲍--Paul/Pao 班--Pan 贝--Pei 毕--Pih 卞--Bein 卜/薄--Po/Pu 步--Poo 百里--Pai-li C: 蔡/柴--Tsia/Choi/Tsai 曹/晁/巢--Chao/Chiao/Tsao 岑--Cheng 崔--Tsui 查--Cha 常--Chiong 车--Che 陈--Chen/Chan/Tan 成/程--Cheng 池--Chi 褚/楚--Chu 淳于--Chwen-yu D: 戴/代--Day/Tai 邓--Teng/Tang/Tung 狄--Ti 刁--Tiao 丁--Ting/T 董/东--Tung/Tong 窦--Tou 杜--To/Du/Too 段--Tuan 端木--Duan-mu 东郭--Tung-kuo 东方--Tung-fang
E: F: 范/樊--Fan/Van 房/方--Fang 费--Fei 冯/凤/封--Fung/Fong 符/傅--Fu/Foo G: 盖--Kai 甘--Kan 高/郜--Gao/Kao 葛--Keh 耿--Keng 弓/宫/龚/恭--Kung 勾--Kou 古/谷/顾--Ku/Koo 桂--Kwei 管/关--Kuan/Kwan 郭/国--Kwok/Kuo 公孙--Kung-sun 公羊--Kung-yang 公冶--Kung-yeh 谷梁--Ku-liang H: 海--Hay 韩--Hon/Han 杭--Hang 郝--Hoa/Howe 何/贺--Ho 桓--Won 侯--Hou 洪--Hung 胡/扈--Hu/Hoo 花/华--Hua 宦--Huan 黄--Wong/Hwang 霍--Huo 皇甫--Hwang-fu 呼延--Hu-yen I: J:
中国姓氏英文翻译大全
中国姓氏英文翻译大全- - [b][u]中国姓氏英文翻译大全- -[/u][/b] A: 艾--Ai 安--Ann/An 敖--Ao B: 巴--Pa 白--Pai 包/鲍--Paul/Pao 班--Pan 贝--Pei 毕--Pih 卞--Bein 卜/薄--Po/Pu 步--Poo 百里--Pai-li C:
蔡/柴--Tsia/Choi/Tsai 曹/晁/巢--Chao/Chiao/Tsao 岑--Cheng 崔--Tsui 查--Cha 常--Chiong 车--Che 陈--Chen/Chan/Tan 成/程--Cheng 池--Chi 褚/楚--Chu 淳于--Chwen-yu D: 戴/代--Day/Tai 邓--Teng/Tang/Tung 狄--Ti 刁--Tiao 丁--Ting/T 董/东--Tung/Tong 窦--Tou 杜--To/Du/Too
段--Tuan 端木--Duan-mu 东郭--Tung-kuo 东方--Tung-fang E: F: 范/樊--Fan/Van 房/方--Fang 费--Fei 冯/凤/封--Fung/Fong 符/傅--Fu/Foo G: 盖--Kai 甘--Kan 高/郜--Gao/Kao 葛--Keh 耿--Keng 弓/宫/龚/恭--Kung 勾--Kou
古/谷/顾--Ku/Koo 桂--Kwei 管/关--Kuan/Kwan 郭/国--Kwok/Kuo 公孙--Kung-sun 公羊--Kung-yang 公冶--Kung-yeh 谷梁--Ku-liang H: 海--Hay 韩--Hon/Han 杭--Hang 郝--Hoa/Howe 何/贺--Ho 桓--Won 侯--Hou 洪--Hung 胡/扈--Hu/Hoo 花/华--Hua 宦--Huan 黄--Wong/Hwang
图像处理外文翻译
杭州电子科技大学 毕业设计（论文）外文文献翻译 毕业设计（论文）题目基于遗传算法的自动图像分割软件开发 翻译（1）题目Image Segmentation by Using Threshold Techniques 翻译（2）题目 A Review on Otsu Image Segmentation Algorithm 学院计算机学院 专业计算机科学与技术 姓名刘xx 班级11xxxxxx 学号1115xxxx 指导教师孔xx
使用阈值技术的图像分割 1 摘要 本文试图通过5阈值法作为平均法，P-tile算法，直方图相关技术（HDT），边缘最大化技术（EMT）和可视化技术进行了分割图像技术的研究，彼此比较从而选择合的阈值分割图像的最佳技术。这些技术适用于三个卫星图像选择作为阈值分割图像的基本猜测。 关键词：图像分割，阈值，自动阈值 1 引言 分割算法是基于不连续性和相似性这两个基本属性之一的强度值。第一类是基于在强度的突然变化，如在图像的边缘进行分区的图像。第二类是根据预定义标准基于分割的图像转换成类似的区域。直方图阈值的方法属于这一类。本文研究第二类（阈值技术）在这种情况下，通过这项课题可以给予这些研究简要介绍。阈分割技术可分为三个不同的类： 首先局部技术基于像素和它们临近地区的局部性质。其次采用全局技术分割图像可以获得图像的全局信息（通过使用图像直方图，例如;全局纹理属性）。并且拆分，合并，生长技术，为了获得良好的分割效果同时使用的同质化和几何近似的概念。最后的图像分割，在图像分析的领域中，常用于将像素划分成区域，以确定一个图像的组成[1][2]。 他们提出了一种二维（2-D）的直方图基于多分辨率分析（MRA）的自适应阈值的方法，降低了计算的二维直方图的复杂而提高了多分辨率阈值法的搜索精度。这样的方法源于通过灰度级和灵活性的空间相关性的多分辨率阈值分割方法中的阈值的寻找以及效率由二维直方图阈值分割方法所取得的非凡分割效果。实验的结果表明，这种方法可以得到的分割结果与详尽二维直方图方法相类似，而计算复杂度与分辨率等级的增加而呈指数下降[3]。 图像的阈值问题，被视为在图像处理的一个重要问题，它不仅可以减少图像数据，同时也奠定了多目标识别和图像认知提供了良好的基础。全局阈值分割和局部阈值的字符图像分割进行了分析。一个新的阈值统计迭代算法，提出要克服的直接阈值，针对一些光照不对称和明显的缺陷，或者更大的数字比例在各种各样的背景灰度图像中。统计迭代阈值分割，基于图像灰度直方图和高斯分布的统计，获得统计迭代法理论表达和最值得阈值法和步骤。航空图像通过分别使用统计迭代算法，直方图技术和自适应方法进行阈值分割。比较三种阈值结果，它表明统计迭代方法大大提高了图像分割的抗噪能力，并且有更好的图像结果，并且不容易在阈值方法中分段[4]。 模糊C均值改进算法和遥感图像分割策略，可以提供较少的迭代次数收敛到全局1Salem Saleh Al-amri1, N.V. Kalyankar2 and Khamitkar S.D 3JOURNAL OF COMPUTING,