We will characterize the worstcase performance of a variety of algorithms for the binpacking problem and the traveling salesman problem. Worst case analysis usually done in the worst case analysis, we calculate upper bound on running time of an algorithm. Systematic changes are made to potentially uncertain payload properties, and the resulting loads are computed. Worst case analysis was, from 1978 until 1986, a doctrine under 40 u.
Participants learn the importance of this analysis and the different methods which can be utilized. Worstcase structural analysis supplemental material qingnan zhou, julian panettay and denis zorinz new york university flora star pendant cow powercog pendant rocking chair dilo test 1 test 2 worstcase force visualizations in this supplement, we provide visualizations of the weakest and second weakest regions for every model in the drop test. That is the question asked during most of the analysis. Efficient load sampling for worstcase structural analysis under force location uncertainty. The results of analysis are used to verify the fitness of structure for use. Linear static, linear dynamic and non linear static paulo b. Combined with a simple ranking based postprocessing step, our method provides a practical solution to worstcase structural analysis problem. Since payload loads are strongly dependent on the frequencies of the payload modes, frequency sensitivity or. Oct 25, 2018 in the context of worst case structural analysis, zhou et al. Your algorithm has di erent runtimes on di erent inputs, and a lot of times we want to know how fast the algorithm runs on an input of a certain size.
Worst case circuit analysis wcca worst case circuit analysis wcca is a technique which, by accounting for component variability, determines circuit performance under a worst case scenario, i. The smaller this gain is, the better the system performance. Efficient load sampling for worst case structural analysis under force location uncertainty. Worst case analysis an overview sciencedirect topics. For linear search, the worst case happens when the element to be searched x in the above code is not present in the array. In order to reduce the number of simulation runs, collating functions can be used to detect differences from the nominal worst case output such as minimum, maximum, or threshold differences. We will characterize the worst case performance of a variety of algorithms for the binpacking problem and the traveling salesman problem. Analysis and design of multi storey structure using etabs. Worstcase analysis equation 2 is rewritten as equation 6 see below, which includes the total tolerance and has been written to obtain the maximum value of the transfer equation. Worst case analysis, electronic partscircuit tolerance analysis,worst case scenario, worst case part. Worstcase circuit analysis wcca or wca is a costeffective means of screening a design to ensure with a high degree of confidence that potential defects and deficiencies are identified and eliminated prior to and during test, production, and delivery. We solve a constrained optimization problem to determine the worst load distribution for a shape that will cause high local stress or large deformations. Structural analysis is an attractive foundation for several reasons. Zpz introduce worstcase structural analysis by extending modal analysis used in dynamic systems to static problems in order to identify weak regions of the structure that may fail.
In the context of worstcase structural analysis, zhou et al. A method to create a worstcase scenario and to detect the worst case minmax values of the outputs and performance attributes of the analog circuits is proposed in this paper. While worst case analysis predicts the critical forces. Wang, yining, ulu, erva, singh, aarti, and kara, levent burak. It is useful to know how much adjustment is required to.
Worst case structural analysis supplemental material qingnan zhou, julian panettay and denis zorinz new york university flora star pendant cow powercog pendant rocking chair dilo test 1 test 2 worst case force visualizations in this supplement, we provide visualizations of the weakest and second weakest regions for every model in the drop test. A worst case effect needs only to be seen once during testing for the analysis to be able to combine it with other worst case events in its analysis. Approximation of the worstcase execution time using. Structural design for the stage mit opencourseware. It is a conservative approach as it only considers the maximum or minimum values of part variation, whichever leads to the worst situation. The maximum stress is then compared against a prespeci. Pdf we present a technique to approximate the worstcase execution time that combines structural analysis with a loopbounding algorithm based on. While the notion of amortization is a natural and reasonable measure of e. Worst case circuit analysis an overview e e c t r n i p sc. We present a method that would identify structural problems in objects designed for 3d printing based on geometry and material properties only, without specific assumptions on loads and manual load setup. Introduction to worst case circuit analysis for the aerospace engineer course overview. Worstcase tolerance analysis is the starting point when creating a tolerance specification it is a conservative approach as it only considers the maximum or minimum values of part variationwhichever leads to the worst situation. This intensive course focuses on the fundamental skills required to perform a worst case circuit analysis wcca.
Reliability and worst case analysis accendo reliability. Lightweight structure design under force location uncertainty arxiv. Analysis of algorithms set 2 worst, average and best cases. Pdf efficient load sampling for worstcase structural. Worstcase circuit analysis can be considered as a step in the softfault diagnosis allowing us to find out the bound outputs or performance attributes of a circuit. The worstcase loading conditions distribution of the load as well as overloading must be considered for the static load case. Worstcase structural analysis acm transactions on graphics. Lateral system analysis tech 3 penn state engineering. In robust control design, performance is expressed and measured in terms of the peak gain the h. Pdf approximation of the worstcase execution time using.
The reactions from the loads imposed on the example building are calculated, the loads on the foundation elements. Structural analysis and design of a warehouse building. Combined with a simple ranking based postprocessing step, our method provides a practical solution to worst case structural analysis problem. A worst case analysis is then performed by setting all the component values to their end tolerance limits which gave an indication of the worst case results. The purchase tolerance can be adjusted with a potentiometer or a dacvariable gain amplifier combination. Efficient load sampling for worstcase structural analysis under. Use wcgain to compute the worstcase sensitivity and complementary sensitivity functions of feedback control structures. Request pdf worstcase load in plastic limit analysis of frame structures this paper addresses the plastic limit analysis of a frame structure under uncertainty. These values were then compared to allowable seismic and wind story drifts as outlined in asce 710. Proceedings of the asme 2018 international design engineering technical conferences and computers and information in engineering conference. Worstcase analysis tries to answer the same questions that statistical analysis does, but rather than varying parameters randomly, you identify what the worst possible values of these parameters may be, and then perform your analysis to see if the system meets its specifications under such circumstances. Robust stability, robust performance and mu analysis analyze and quantify the robustness of feedback control systems with uncertainty, and understand the relationship between robustness and the structured singular value. Sandler is responsible for the design, worst case analysis. Steel reaction frame report home northeastern university.
We present a technique to approximate the worstcase execution time that combines structural analysis with a loopbounding algorithm based on local induction variable analysis. The worst case method of the stack up analysis is the simplest among all the methods used in industry. Introduction to worst case circuit analysis for the aerospace. Assembly tolerance chain stack up analysis is used for calculating the tolerance value of the overall assembly or a gap in the assembly from the tolerance values of the individual components. The objective of the thesis is to improve the design of a warehouse building. Efficient load sampling for worstcase structural analysis. Worstcase optimization of structures weak in tension. Worstcase load in plastic limit analysis of frame structures request. In this chapter we demonstrate one important tool, referred to as worst case performance analysis, which establishes the maximum deviation from optimality that can occur for a given heuristic algorithm. Aarti singh carnegie mellon school of computer science. The worst case in each direction, for both wind and seismic were considered.
In this project multistoreyed construction, we have adopted limit state method of analysis. Structural analysis and evaluation september 2008 8. For example, the part stress analysis psa, the worst case performance analysis wca, and fatigue life of mechanical elements solder joints, connectors, etc. Foundation analysis and design examples chapter 3 described the types of loads considered in this manual. In this chapter we demonstrate one important tool, referred to as worstcase performance analysis, which establishes the maximum deviation from optimality that can occur for a given heuristic algorithm. The results indicate that our approach achieves significant improvements over the existing work and brute force approaches. A comparison between worst case structural analysis zhou et al. Efficient load sampling for worstcase structural analysis under force location uncertainty y. The worst case method simply adds the dimensions using the extreme values for those dimensions. Finite element analysis was used to check stresses in the members for different loading cases.
Worst case circuit analysis an overview e 1 e c t r o n i c p art sc i r cu i t s to 1 er an ce an a 1 y s i s walter m. Offsite consequence analysis referred to as ocagd in this course the calculation of worst case scenario wcs is required for applicable stationary sources per epas rule in 40 cfr part 68 chemical accident prevention rule or cap see the link below the wcs for a process or vessel is the release of the largest quantity of a listed. Without structural analysis, structures could be unstable and potentially dangerous. Story drifts were found directly from the etabs model. Worst case analysis wca of electronic circuits has been a standard way of showing that a circuit meets the minimum design requirements as defined by the customer. Typically, the small sections of software can be measured automatically using techniques such as instrumentation adding markers to the software or with hardware support such as debuggers, and. Ap proximation methods that reduce the total number of fea runs are mandatory to make the stress prediction and structure opti mization. Analysis shows areas of concern allowing the item to be redesigned before it is produced therefore saving time and money. The worst case loading conditions distribution of the load as well as overloading must be considered for the static load case. This appendix demonstrates how these loads are calculated using a sample building and foundation. Moving aerospace structural design practice to a load and. In addition, it also creates a safer environment for the customer and prevents injury due to failure of the structure. The maximum drifts in both the ns and ew directions were controlled by loads due to seismic. For such purpose, one of the authors presented a worstcase design of structures based on a random sampling approach, in which constraints are assigned on the worst.
Worstcase design of structures using stopping rules in k. Finiteelement analysis fea is the standard technique that. Worst case analysis equation 2 is rewritten as equation 6 see below, which includes the total tolerance and has been written to obtain the maximum value of the transfer equation. His research interests lie primarily in the domain of physical simulation, geometry processing, and optimizationbased inverse design for digital fabrication. We must know the case that causes maximum number of operations to be executed. Worst case runtime means that you are feeding the worst possible input of that size into your algorithm. Worstcase execution time estimation of softreal time java applications. In the context of worst case structural analysis, zhou et al. Worst case tolerance analysis is the starting point when creating a tolerance specification. Sandler has over 30 years experience in the design and analysis of power conversion equipment for military and space applications. The approach that is typically followed is to define worst case component variations based on temperature, aging, radiation and purchased tolerances. The design load is taken from the worst case analyzed or from a statistical combination of all cases.
618 543 943 1175 1448 286 437 1591 444 1204 464 1397 698 964 955 690 1393 259 775 801 766 1104 920 932 1243 303 1330 596 762 1238 281 435 1648 122 1405 776 861 1088 189 818 1195 641