Estimation of the kinetic energy dissipation in fall-arrest system and manikin during fall impact

Fall-arrest systems (FASs) have been widely applied to provide a safe stop during fall incidents for occupational activities. The mechanical interaction and kinetic energy exchange between the human body and the fall-arrest system during fall impact is one of the most important factors in FAS ergonomic design. In the current study, we developed a systematic approach to evaluate the energy dissipated in the energy absorbing lanyard (EAL) and in the harness/manikin during fall impact. The kinematics of the manikin and EAL during the impact were derived using the arrest-force time histories that were measured experimentally. We applied the proposed method to analyse the experimental data of drop tests at heights of 1.83 and 3.35 m. Our preliminary results indicate that approximately 84-92% of the kinetic energy is dissipated in the EAL system and the remainder is dissipated in the harness/manikin during fall impact. The proposed approach would be useful for the ergonomic design and performance evaluation of an FAS. STATEMENT OF RELEVANCE: Mechanical interaction, especially kinetic energy exchange, between the human body and the fall-arrest system during fall impact is one of the most important factors in the ergonomic design of a fall-arrest system. In the current study, we propose an approach to quantify the kinetic energy dissipated in the energy absorbing lanyard and in the harness/body system during fall impact.     

SimpleScalar: an infrastructure for computer system modeling

Designers can execute programs on software models to validate a proposed hardware design's performance and correctness, while programmers can use these models to develop and test software before the real hardware becomes available. Three critical requirements drive the implementation of a software model: performance, flexibility, and detail. Performance determines the amount of workload the model can exercise given the machine resources available for simulation. Flexibility indicates how well the model is structured to simplify modification, permitting design variants or even completely different designs to be modeled with ease. Detail defines the level of abstraction used to implement the model's components. The SimpleScalar tool set provides an infrastructure for simulation and architectural modeling. It can model a variety of platforms ranging from simple unpipelined processors to detailed dynamically scheduled microarchitectures with multiple-level memory hierarchies. SimpleScalar simulators reproduce computing device operations by executing all program instructions using an interpreter. The tool set's instruction interpreters also support several popular instruction sets, including Alpha, PPC, x86, and ARM     

Geometrically exact physics-based modeling and computer animation of highly flexible 1D mechanical systems

This paper presents a geometrically exact beam theory and a corresponding displacement-based finite-element model for modeling, analysis and natural-looking animation of highly flexible beam components of multibody systems undergoing huge static/dynamic rigid-elastic deformations. The beam theory fully accounts for geometric nonlinearities and initial curvatures by using Jaumann strains, concepts of local displacements and orthogonal virtual rotations, and three Euler angles to exactly describe the coordinate transformation between the undeformed and deformed configurations. To demonstrate the accuracy and capability of this nonlinear beam element, nonlinear static and dynamic analysis of two highly flexible beams are performed, including the twisting a circular ring into three small rings and the spinup of a flexible helicopter rotor blade (Graphical abstract). These numerical results reveal that the proposed nonlinear beam element is accurate and versatile for modeling, analysis and 3D rendering and animation of multibody systems with highly flexible beam components.     

Assessment of the strategies for effective implementation of computer integrated manufacturing systems (CIMS)

There have been enormous amounts invested by manufacturing firms in the United States and elsewhere around the world in CIMS. Published reports of these CIMS implementations have shown mixed results, some failures and some notable successes. This paper provides an outline of an ongoing research which is expected to extract and synthesize the general implementation success factors delineated from past implementation efforts, and is expected to serve as a guide for future efforts to implement CIMS.     

Temperature-aware computer systems: Opportunities and challenges

Temperature-aware design techniques have an important role to play in addition to traditional techniques like power-aware design and package- and board-level thermal engineering. The authors define the role of architecture techniques and describe hotspot, an accurate yet fast thermal model suitable for computer architecture research.     

Theory of fault-based predicate testing for computer programs

Predicates appear in both the specification and implementation of a program. One approach to software testing, referred to as predicate testing, is to require certain types of tests for a predicate. In this paper, three fault-based testing criteria are defined for compound predicates, which are predicates with one or more AND/OR operators. BOR (boolean operator) testing requires a set of tests to guarantee the detection of (single or multiple) boolean operator faults, including incorrect AND/OR operators and missing/extra NOT operators. BRO (boolean and relational operator) testing requires a set of tests to guarantee the detection of boolean operator faults and relational operator faults (i.e., incorrect relational operators). BRE (boolean and relational expression) testing requires a set of tests to guarantee the detection of boolean operator faults, relational operator faults, and a type of fault involving arithmetical expressions. It is shown that for a compound predicate with n, n>0, AND/OR operators, at most n+2 constraints are needed for BOR testing and at most 2*n+3 constraints for BRO or BRE testing, where each constraint specifies a restriction on the value of each boolean variable or relational expression in the predicate. Algorithms for generating a minimum set of constraints for BOR, BRO, and BRE testing of a compound predicate are given, and the feasibility problem for the generated constraints is discussed. For boolean expressions that contain multiple occurrences of some boolean variables, how to combine BOR testing with the meaningful impact strategy (Weyuker et al., 1994) is described     

Direct testing of methods for computer image processing

An empirical approach to estimating the performance of image processing programs based on the standardized set of references subjected to controlled distortions is proposed. Examples of applying the approach to programs for boundary detection, restoration, and segmentation are given.     

Standby redundancy: Crash-tolerant computers for distributed computer systems

Distributed systems allow greater overall availability. Standby redundancy can be incorporated into application software to improve availability in the event of a crash. The Tandem-16 is an example of crash-tolerant computers. Other examples include Prosur, intended for a hostile environment, and Demos M/P, which uses a broadcast network and a computer called the ‘recorder’. Local area networks can introduce greater vulnerability.     

Assessment of sharp- and continuous-interface methods for drop in static equilibrium

Among the successful approaches for treating multiphase problems involving an interface, the continuous-interface method often handles the surface force via a locally integrated body force formulation. On the other hand, the sharp-interface method treats each phase separately while coordinating them via an explicit interface treatment. The sharp interface method computationally more demanding, but the continuous interface method can create spurious velocity in the interface region, which compromises the solution accuracy. Furthermore, the large property jumps often observed between liquid and vapor phases can influence the numerical accuracy, and needs to be investigated. In order to quantitatively demonstrate the relative performance of the sharp- and continuous-interface methods, we have considered a spherical drop in static equilibrium to highlight the role of the interface treatment. It is shown that the sharp-interface method is second-order accurate while the continuous-interface method is first-order. Furthermore, the sharp interface method is insensitive to the property jumps.     

便携式注水井压降测试仪的研制

为了提高油田调剖堵水的效果,对井口压降曲线分析地层特性进行了研究,设计了新的测试仪器.该系统包含连接支承装置,便于仪器安装,选用了AT89C52、AD7714和AT24C256等低功耗元件,保证了系统的可靠性,实现了便携式测量.该仪器能快速、准确地完成注水井压力的采集和分析处理,直观的输出处理结果,为注水井调剖提供可靠的决策依据,已在油田现场得到了成功应用.     

On a class of operators for expert systems

We use the concept of directed algebra (closely related to De Morgan triplets) to modelize connectives in expert systems when linguistic terms are introduced. Mainly this article describes all directed algebra structures on a totally ordered finite set. © 1993 John Wiley & Sons, Inc.     

Analytical and computer modeling of work scheduling

Mathematical models studying work-rest schedules in a production process are developed and conditions are established to derive an optimal work rest schedule to maximize work output per unit time. A CSMP simulation study compares the proposed theoretical policy with two alternate policies and tests the sensitivity of the results for the different cases. Finally, the technique of dynamic programming is used to solve the work-rest schedule under a finite time horizon. The paper stresses approaches and methodology of study.     

Modeling robustness behavior using aspect-oriented modeling to support robustness testing of industrial systems

Model-based robustness testing requires precise and complete behavioral, robustness modeling. For example, state machines can be used to model software behavior when hardware (e.g., sensors) breaks down and be fed to a tool to automate test case generation. But robustness behavior is a crosscutting behavior and, if modeled directly, often results in large, complex state machines. These in practice tend to be error prone and difficult to read and understand. As a result, modeling robustness behavior in this way is not scalable for complex industrial systems. To overcome these problems, aspect-oriented modeling (AOM) can be employed to model robustness behavior as aspects in the form of state machines specifically designed to model robustness behavior. In this paper, we present a RobUstness Modeling Methodology (RUMM) that allows modeling robustness behavior as aspects. Our goal is to have a complete and practical methodology that covers all features of state machines and aspect concepts necessary for model-based robustness testing. At the core of RUMM is a UML profile (AspectSM) that allows modeling UML state machine aspects as UML state machines (aspect state machines). Such an approach, relying on a standard and using the target notation as the basis to model the aspects themselves, is expected to make the practical adoption of aspect modeling easier in industrial contexts. We have used AspectSM to model the crosscutting robustness behavior of a videoconferencing system and discuss the benefits of doing so in terms of reduced modeling effort and improved readability.     

Overview: New directions for simulation and modeling of complex systems

New modalities for simulation and modeling of complex systems are developing which are based on networked clusters of desktop workstations. This direction is driven mainly by sharply decreasing costs of high performance CMOS microprocessors. This path is further augmented by the trans-national deployment of wide-band communication technology which can economically link national or university-based supercomputer facilities for modeling of very large scale systems and also link local clusters to a supercomputer. Cluster-directed applications briefly outlined in this overview include modeling of compressed viscous flow, performance of wireless and ATM communications systems, and innovations in cluster architecture.     

Physically-based modeling,simulation and rendering of fire for computer animation

We give an up-to-date survey on techniques and methods for fire simulation in computer graphics. Physically-based method prevails over traditional non-physical methods for realistic visual effect. In this paper, we explore visual simulation of fire-related phenomena in terms of physically modeling, numerical simulation and visual rendering. Firstly, we introduce a physical and chemical coupled mathematical model to explain fire behavior and motion. Several assumptions and constrains are put forward to simplify their implementations in computer graphics. We then give an overview of present methods to solve the most complicated processes in numerical simulation: velocity advection and pressure projection. In addition, comparisons of these methods are also presented respectively. Since fire is a participating medium as well as a visual radiator, we discuss techniques and problems of these issues as well. We conclude by addressing several open challenges and possible future research directions in fire simulation.