K. L. Chui, W. K. Chiu and K. M. Yu.

Robotics and Computer-Integrated Manufacturing, Vol. 24, No. 2, Apr. 2008, pp. 270-286.

In reverse engineering, geometrical information of a product is obtained directly from a physical shape by a digitizing device. To fabricate the product, manufacturing information (usually tool-path) must be generated from a CAD model. The data digitized must be processed and in most cases, a surface model is constructed from them using some of the surface fitting technologies. However, these technologies are usually complicated and the process for constructing a surface patch from a massive digitizing data is time-consuming. To simplify the process for getting tool-path information, a simple algorithm is proposed in this paper. The algorithm is used to generate a 5-axis machining tool-path. Instead of implementing any complicated surface fitting techniques, a direct method is proposed for constructing three-dimensional (3D) triangular mesh from the digitizing data with the mesh points considered as the tool contact locations. Depending on the locations of the points digitized, a decimation procedure is applied such that some of the digitizing data will be filtered out. Then, the tool axis orientations which must be determined in 5-axis tool-path are calculated and the tool center locations are determined accordingly. A 3D biarc fitting technique is applied for all the tool center locations so that a complete 5-axis tool-path is obtained.

X. Zhang, X. Jin, Y. Li and G. Li.

Materials and Design, Vol. 29, No. 2, 2008, pp. 403-410.

In a traffic accident, a commercial vehicle in the developing stage crashed against a wall due to the faulty operation of the driver. According to the result of the analysis, the speed of the vehicle was 50km/h at the moment of contact, and the angle between the tire mark and the wall was 17 super(o). In the accident, it was found that the hinge of the engine hood went fractured. The limitation of the design was also shown in the simulation result and the real crash tests of the standard test that forced the vehicle to crash against the rigid wall at the speed of 50km/h. To solve the problem, the design of the outer and the inner panel was modified on the one hand, and the high strength steel was applied on fourteen energy-absorbing parts on the otherhand. The simulation result showed that the new design could greatly improve the crashworthiness of the vehicle, and provided a solution to the hinge problem as well.

Michael Fox, Richard Hastings, Scott Lovald and Juan Heinrich.

Journal of Failure Analysis and Prevention, Vol. 7, No. 3, June 2007, pp. 165-174.

A failure analysis case study is presented for a two-piece aerosol containing tetrafluoroethane, commonly referred to as Refrigerant 134a. A gentleman was preparing to recharge the air conditioning system of an automobile when the bottom exploded off the aerosol container, propelling the body of the aerosol container like a rocket, which hit the man in the eye and blinded him in that eye. The aerosol was never connected to the air conditioner, therefore backpressure from the air conditioner (AC) compressor was ruled out as a cause for the explosion. The objective of the study was to determine why the aerosol exploded. Several recently developed test methods were used, including two types of heat-to-burst tests and a puncture chamber to measure the pressure-versus-temperature behavior of aerosols. More common test methods were also used, such as water bath pressure tests, hydro pressure burst tests, pneumatic pressure burst tests, hardness measurements, weight measurements, metallography, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and an accident scenario recreation. A semi-empirical correlation between the hardness and weights of the container bottoms was used to determine the explosion temperature and/or pressure. This semi-empirical correlation agrees in principle with an analysis of the explosion pressures using finite-element analysis (FEA). The root cause for the explosion was determined to be a lack of strength of the bottom of the two-piece aerosol coupled with heating the aerosol to temperatures significantly above room temperature.

J. Hallahan.

PAR Government Systems Corp., Oct 2007, pp. 80.

The primary objective of this project was to research and develop applied computer forensic approaches for preventing and detecting insider threats in sensitive organizations in conjunction with advanced access control systems such as Fine-grained, Active, and Scalable Access Control (FASAC). Access Control is the fundamental basis of computer security, but still remains a relative weakness in dealing with everyday threats, especially those posed by insiders. To address the insider threats against critical information systems, an advanced access control approach was investigated that supports fine-grained, active, and scalable access control services.

Jean H. Slane, Robert J. Butler, John J. Emmerling, Steven L. Morris, Robert C. Winn and Krista B. Kumley.

AIAA Modeling and Simulation Technologies Conference Proceedings, 2007.

Flight data recorders are not required for general aviation aircraft that carry less than ten passengers. Following an accident, there may be little or no recorded information with which to determine the cause. Conventional recorders must tap into aircraft systems, making the cost prohibitive for general aviation. A flight data recorder has been designed which requires only aircraft power and a GPS antenna. The instrumentation consists of the GPS and a three-axis accelerometer. Using basic aircraft equations of motion, virtually all flight parameters of interest can be reconstructed. The validity of the reconstruction was examined by performing a flight test in which several dynamic maneuvers were performed. In this paper reconstructed parameters are compared to flight instrument data for a steep turn, a spiral, a power-off stall and a cross - control maneuver. Results show that important parameters such as roll angle, airspeed, altitude and acceleration can be accurately reproduced.

J. S. Tschan.

Journal of Imaging Science and Technology, Vol. 51, No. 4, July-Aug. 2007, pp. 299-309.

The extremely wide range of inkjet and laser printing equipment renders it difficult to establish links between counterfeiters or forgers and the documents that they produce. As part of a solution to this problem, a forensically useful method was developed for measuring banding effects in laser printers and photocopiers, which can be used to establish a link between a document and the machine on which it was produced. The method involves the analysis of high spatial resolution and low noise digital images to measure the sharpness, intensity and size characteristics of individual printed text characters. The relative variations in these measurements can then be used to identify the individual machine on which the document in question was originally printed. In tests, it was possible to distinguish between three machines, one of which also showed differences in the print produced when the toner cartridge was changed. (14 fig, 11 ref)

Abdullah Kakar and Dennis Crider.

AIAA Modeling and Simulation Technologies Conference Proceedings, 2007.

The Flight Data Recorder (FDR) is one of the most critical sources of data the National Transportation Safety Board uses for accident investigations. The various parameters recorded on the FDR can provide information about the sequence of events that led to the accident. However, sometimes a parameter of interest may not be available or may have become corrupted. The Safety Board can extract the necessary parameters using the Safety Board's simulation tool and the available FDR and radar data. As an example, the August 15, 2005 MD-82 accident near Machiques, Venezuela, will be used to illustrate how the angle of attack, pitch angle and engine data were extracted using the simulation tool, which helped to understand aircraft performance characteristics.

H. G. Schaathun.

IEEE Transactions on Information Forensics and Security, Vol. 1, No. 2, June 2006, pp. 248-255.

Digital fingerprinting is a forensic method against illegal copying. The distributor marks each individual copy with a unique fingerprint. If an illegal copy appears, it can be traced back to one or more guilty pirates due to this fingerprint. To work against a coalition of several pirates, the fingerprinting scheme must be based on a collusion-secure code. This paper addresses binary collusion-secure codes in the setting of Boneh and Shaw (1995/1998). We prove that the Boneh-Shaw scheme is more efficient than originally proven, and we propose adaptations to further improve the scheme. We also point out some differences between our model and others in the literature.

Ergin Atimtay and Recep Kanit.

Practice Periodical on Structural Design and Construction, Vol. 11, No. 3, Aug. 2006, pp. 149-160.

Visiting an earthquake damaged town is like visiting a gigantic structural testing laboratory. A carefully conducted forensic engineering can reveal much insight on the nature of earthquakes and the fundamental principles of seismic design. The earthquake devastated area is sufficient proof that earthquakes release a tremendous amount of energy. This energy propagates in all directions and enters a structure as ground motion which has displacement, velocity, and acceleration components. The seismic energy which is introduced into the structure must be dissipated within the structure. Energy dissipation shows itself mainly as inelastic behavior of the structural system. The structure must be damaged to dissipate energy. If seismic energy is dissipated at locations which make the structure unable to satisfy equilibrium of forces, collapse is inevitable. An earthquake resistant structure should dissipate seismic energy as damage in the structural system, but collapse should not occur. What is more, after the earthquake, damage should be economically feasible to repair. Observations reveal that beam-column joints and column ends are wrong locations to dissipate seismic energy. Shear failures and anchorage failures of reinforcing bars are wrong types of damage which dissipate very little energy and lead to collapse. Short columns and soft or weak stories must be strictly avoided. Longitudinal and transverse reinforcement should be well detailed and anchored. A successfully designed and constructed building should contain shear walls conforming to the year 2000 requirements of the AO. In the wide earthquake devastated area, observations reveal that no buildings have collapsed which contain shear walls as part of the structural system. Shear walls are the seismic collapse insurance of a building. A successfully designed and constructed building should not sway out of control, should dissipate seismic energy by flexural plastification at bottom of shear walls and ends of beams. The occurrence of shear failure before flexural failure should never be permitted.

C. Gagg.

Engineering Failure Analysis, Vol. 12, No. 5, Oct. 2005, pp. 784-807.

Every year in the UK more than 4000 people die in accidents in and around the home and nearly three million turn up at accident and emergency departments seeking treatment. Intrinsic in this number are many incidents of injury or death directly attributable to poor product design or manufacture of domestic products. In and around the home, commodities that dominate so much of every-day life are becoming more numerous and complex and could be mooted as an argument for such dire statistics. Moreover, society in general is becoming more litigious. These converging trends are responsible for an increasing significance of product liability. When property is damaged, personal injury sustained or loss of life occurs there is an understandable need to determine where any fault may lie. The forensic (or failure) engineer will glean relevant information through meticulous investigation and a reverse engineering process. Reconstructing the failure will uncover any inherent defect in product design, manufacturing, incorrect installation or maintenance. However, product failure can also be attributable to careless use or abuse by the individual, rather than to any specific defect or design shortcoming being inherent within a product. Ultimately the outcome of any investigation will be a sound finding and a conclusion that clearly describes what happened and why. To illustrate typical failure modes that are currently emerging in the home-based UK market, a range of domestic product failures are presented from the author's forensic casebook.

Anonymous

Aerospace Engineering, Vol. 25, No. 4, May 2005, pp. 22-23.

"Black boxes" carried on aircraft record data-such as speed, altitude, and crew conversations-that can be recovered after an accident to help investigators learn the cause of a mishap. The black box often includes a beacon that helps investigators find the box. The use of black boxes on spacecraft had been thought impossible because they would tend to burn up during re-entry, said Dan Rasky, a scientist at NASA Ames Research Center. However, NASA and The Aerospace Corporation have now agreed that the time might be right to try to develop a spacecraft black box, among many other low-cost, miniature space systems.

L. C. da Silva Nunes and dos Santos,Paulo Acioly M.

Proc.SPIE, Vol. SPIE-5622, 2004, pp. 208-212.

We present an application of the use of stereoscope to recovering obliterated firearms serial number. We investigate a promising new combined cheap method using both non-destructive and destructive techniques. With the use of a stereomicroscope coupled with a digital camera and a flexible cold light source, we can capture the image of the damaged area, and with continuous polishing and sometimes with the help of image processing techniques we could enhance the observed images and they can also be recorded as evidence. This method has already proven to be useful, in certain cases, in aluminum dotted pistol frames, whose serial number is printed with a laser, when etching techniques are not successful. We can also observe acid treated steel surfaces and enhance the images of recovered serial numbers, which sometimes lack definition.

M. S. LESNEY.

Today's Chemist at Work, Vol. 13, No. 10, pp. 15-16, 2004, October.

Mass spectrometry (MS) is a technique to identify chemicals in a substance by their mass and charge. Mass spectrometers essentially weigh molecules and measure how much of a compound is present in small mixtures. MS is extremely useful in forensic science, which traces sources of materials from crime scene events and has evolved directly with instrumentation capability to analyze minute amounts of evidence. A small carpet fiber found at a crime scene can be analyzed by MS to identify the types and ratio of the dyes used in the carpet and to pinpoint the manufacturer(s) of that type of carpet. Microspectrophotometry (instrument measuring energy emitted by minute samples) is a nondestructive technique currently used for evaluating the spectral fingerprint of the composite dye mixture providing ratio of dyes. Thin layer chromatography (TLC), migration of a liquid sample by capillarity through a thin solid adsorbent layer of alumina or silica gel on a rigid glass support, complements microspectrophotometry by identifying the dyes. Capillary electrophoresis and micro-high performance liquid chromatography (HPLC) are available alternative techniques. Electrospray ionization mass spectrometry (ESI MS) is an extremely sensitive and reproducible technique for spectral analysis of small samples. Tandem MS using two mass spectrometers connected in series by a collision cell can further analyze the ESI MS results. Laser ablation inductively coupled plasma MS (LA-ICPMS) is an extremely sensitive technique producing quick results in detecting trace elements without elaborate destructive sample preparation. Although comprised of limited common elements, glass and steel have wide variations in trace elements that can be detected and analyzed successfully using LA-ICPMS. Recently, glass fragments and carbon steel alloys were analyzed using principal component analysis (PCA), a transform that simplifies data from LA-ICPMS. PCA is a suitable data reduction method for LA-ICPMS, producing score plots or fingerprints of data clusters for comparison. PCA generates its own quality control, choosing the appropriate elements for comparison. Use of highly sophisticated MS techniques is now limited only by the availability of libraries of standards for sample comparison. Criminologists and forensic scientists are creating their own standard libraries to optimize use of evolving advanced MS.

Patrick J. Smith, Phelim ODoherty, Carlos Luna and Sean McCarthy.

Proc.SPIE, Vol. SPIE-5616, 2004, pp. 40-46.

We describe an optical forensic method for tracing a CD back to the pressing machine in which it was created, and present a system we have developed which maintains a library of the 'fingerprints' of such machines and can compare sample CDs against this library. In principle, any security feature that is deliberately created can be copied by a counterfeiter. In our forensic method we concentrate on features that arise spontaneously in the manufacturing process. Such features act as a signature or 'fingerprint'. In the case of CDs we show how the molding process leaves an imprint of an unpolished part of the 'mirror plate' on the CD surface. Using machine vision and pattern-matching, we demonstrate the use of the system to acquire a positive match of a sample against a pre-recorded library entry created using a different CD from the same mould.

Wade D. Bartlett, Bill Wright, Oren Masory, et al.

When performing calculations pertaining to the analysis of motor vehicle accidents, investigators must often select appropriate values for a number of parameters. The uncertainty of the final answers is a function of the uncertainty of each parameter involved in the calculation. This paper presents the results of recent tests conducted to obtain sample distributions of some common parameters, including measurements made with tapes, measurements made with roller-wheels, skidmark measurements, yawmark measurements, estimation of crush damage from photographs, and drag factors, that can be used to evaluate the uncertainty in an accident reconstruction analysis. The paper also reviews the distributions of some pertinent data reported by other researchers.

J. B. Bowles.

USA, 2002,

Failure Modes and Effects Analysis (FMEA) has evolved into a powerful tool that can be used by design engineers during all phases of product development to enhance product safety and reliability by eliminating or mitigating the potential effects of item failures. FMEA consists of examining the modes and causes of item failures and determining the product response to the failures. Steps can then be taken to change the design in order to eliminate the failure, mitigate its effects, or develop compensating provisions in case the failure should occur. A structured approach to the FMEA ensures that all appropriate failure modes are analyzed, that the system satisfies its fault mitigation requirements, and that these requirements are properly allocated. The FMEA methodology can be usefully employed throughout the design cycle from conceptual design to production and deployment. Tools have been developed to reduce the amount of labor required for the analysis and to evaluate hardware-, software-, material-, and process-related causes of failure. Significant progress is also being made in automated tools to facilitate the analysis. This article describes the methodology for performing an FMEA. The overview section describes the process with the specific example of a hot water heater, followed by a discussion of the role of FMEA in the design process. The second section describes the analysis procedures and shows how proper planning, along with functional, interface, and detailed fault analyses, makes FMEA a process that can contribute to the design throughout the product development cycle. The third section describes the use of fault equivalence to reduce the amount of labor required by the analysis. The next section shows how fault trees are used to unify the analysis of failure modes caused by design errors, manufacturing and maintenance processes, materials, and so on, and to assess the probability of the failure mode occurring. The last section describes some of the approaches to automating some of the analysis.

C. O. Smith.

USA, 2002,

Products liability is a legal term for the action whereby an injured party (plaintiff) seeks to recover damages for personal injury or property loss from a producer and/or seller (defendant) when the plaintiff alleges that a defective product caused the injury or loss. If a products liability suit is entered against a company, the plaintiff's attorney and technical experts attempt to convince a jury that the manufacturer did not exercise reasonable care in one or more features of design and/or manufacture, and that because the company did not exercise reasonable care, an innocent party was injured. The defendant's team attempts to convince a jury that the manufacturer was not responsible for the injury. Products liability is not new. The first law code known to be in writing was established by Hammurabi, King of Babylon, about 4000 years ago, and it contained clauses that clearly relate to products liability.

H. Hollien.

New York, Plenum Press, 1990.

Intended for scientists, engineers, technicians, attorneys, and law enforcement personnel, this book examines the problems and issues associated with forensic phonetics. Part I discusses basic issues in acoustics including simple acoustics; how speech is produced, coded, and perceived; and the nature of such instruments as microphones, earphones, and tape recorders. Part II considers the sources of forensic problems on tape recordings and what to do about them. Topics discussed are the various forms of electronic surveillance and the tape recording of evidence, the characteristics of distortion and noise, the decoding process/techniques and problems with courtroom transcripts, and the authentication of tape recordings. Part III addresses the identification of speakers from their voice alone. Issues covered are voice identification by aural-perceptual means, the use of human listeners to make aural-perceptual judgments of a talker's identify, the voiceprint approach to speaker identification and its limitations, and machine or computer-assisted approaches to voice identification. Part IV addresses the general problem of detecting stress in the human voice. One chapter in this part considers the implications of vocal stress for polygraph examinations. Part V addresses language evaluation for forensic purposes, forensic psychoacoustics, the pirating of tape recordings, and crimes involving computers. 513 references, chapter tables, and a subject index

Z. M. Gorski, A. German and E. S. Nowak.

Journal of forensic sciences, Vol. 35, No. 1, January 1990, pp. 69-79.

In moderate to severe collisions, large decelerations and hence large forces are generated. Various components of the seat belt system are loaded, and physical evidence of this loading may be observed long after the collision event. Such witness marks result from interaction between different components of the restraint system, or between the restraint and portions of the vehicle interior. Detailed examination and analysis of such marks can establish whether or not the seat belt was in use and also the precise manner in which the seat belt was worn. Such investigative techniques are critical for evaluating the collision performance of occupant restraint systems and for positively identifying cases of restraint system misuse. This paper reviews the types of physical evidence which may be observed to determine restraint usage. 12 figures, 3 references. (Author abstract)

M. L. Young.

Forensic Engineering, Vol. 1, No. 4, 1988, pp. 105.

Vehicular accident reconstruction is a field where highly trained engineers and lawyers sort out information acquired from tangled wreckage, skid marks, eye witness testimony, and police reports. This data is skillfully collected and then carefully evaluated with microcomputers that simulate the accident. An introductory literature search was performed to help put the mass of public accident reconstruction information at the fingertips of the forensic engineer. Many articles abstracted discuss the presentation of accident reconstruction scenarios to the jury, including advice on graphics, visual aids, computer simulation, and even videotaping. Technical abstracts include information on the inaccuracies of existing accident reconstruction simulation programs, forklift accident reconstruction, vehicular impact into water, vehicle-rail accidents, and motorcycle accident reconstruction.

Duc Tran and Estela Hernandez.

AIAA Modeling and Simulation Technologies Conference and Exhibit; Providence, RI; August 16-19, 2004.

As part of the investigation of the accident involving American Airlines Flight 587, the National Transportation Safety Board (NTSB), in cooperation with NASA Ames Research Center, proposed to conduct observations and tests using the Vertical Motion Simulator (VMS). The investigation was divided into two phases. Phase I consisted of evaluating the accelerations experienced during the accident event by back-driving the cockpit controls, displays, out-the-window scene, cockpit communications, and motion of the aircraft as recorded and derived from the aircrafts flight data recorder (FDR) and cockpit voice recorder (CVR). Phase II consisted of evaluating the effects of flight control characteristics and accelerations similar to those experienced during the accident event on pilot perception and performance using a tracking task. The tracking task consisted of pilots following an on-screen target with various flight control configurations, with both motion off and motion being back-driven using derived acceleration data from the FDR. This paper describes the work provided by the VMS in support of the investigation and does not include any conclusions drawn from the study.