Hybrid Program Dependence Approximation for Effective Dynamic Impact Prediction

Dynamic impact analysis based on program executions has shown promise in aiding tasks in the life cycle of large-scale systems. Dynamic impact analysis techniques have shown to produce more precise results than static impact analysis [1]. However, current dynamic impact analysis techniques lack important features such as analysis of dependency among program entities and consideration of object-oriented programs ' features. Thus they may produce imprecise results. In this paper, we present a precise dynamic impact analysis approach for object-oriented programs. This approach considers the characteristics of object- oriented programs and performs dependency analysis which may potentially reduce the impact sets by eliminating elements that do not have dependency on the changed elements. Even though our discussion in this paper is based on Java <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">TM</sup> programming language, this approach can be carried out in a language independent manner for broader applications.

Gamma irradiation of food packaging materials: an NMR study

A significant portion of the research on spiral bevel gear focused on contact stress and assembly flexibility (V and H check) values, while only a few studies investigated the relationship between transmission errors and rotational speed. This paper addresses and discusses an approach for 3D dynamic contact and impact analysis of spiral bevel gear drives. Dynamic models considering friction, gear clearance, and time-varying stiffness were established. Finite element software was utilized to analyze the dynamic responses of gear transmission, surface contact stress, and root bending stress of a spiral bevel gear pair. The dynamic model simulated the vibration behavior of an actual gear set under dynamic loading. The dynamic responses of the spiral bevel gear drives were obtained under differential rotational speeds of the driver and the driven resistance. The stiffness and elastic deformation of gear teeth were calculated using the finite element method with actual geometry and gear positions. After the impact analysis, the numerical simulation results of transient and steady-state transmission errors are obtained simultaneously. Using the fast Fourier transform method, frequency spectrums of the transient and steady states of the calculated transmission errors are obtained to enable the gearbox designer to avoid the resonance zone.

The hanging net shielding system, employing a suspended cage-type enclosed structure to restrict the high-voltage transmission wire, has seen increasingly widespread application in transmission line crossing construction. However, the lack of a comprehensive dynamic analysis methodology has limited the standardization of its design and usage. In this investigation, a systematical dynamic modeling and analysis procedure of the hanging net shielding system is proposed based on the absolute nodal coordinate formulation (ANCF). The carrier cable, slings and transmission wire are discretized by the ANCF cable element. The spatial flexible beam–beam contact model and the assumption of a single contact area are adopted to perform the contact searching between the transmission wire and the horizontal pulley. The system dynamics analysis equation is assembled and solved by generalized alpha method. A full-scale model is simulated for the transmission wire impact condition and the variation history of the tension in carrier cable and the sling cable are given. The peak value of the tension in carrier cable could be 110 kN, while the largest tension in sling cable is 9 kN. Results could help to ensure construction safety, shorten the design cycle of the protection system and reduce the development cost at the same time.

The visible light indoor position perception method not only solves the limitations of traditional positioning technology indoors, but also promotes innovation in fields such as smart retail and healthcare with its advantages of high accuracy and low cost. At present, visible light indoor positioning methods based on received signal strength are restricted by issues such as environmental interference and poor signal stability. Additionally, traditional feature extraction methods result in insufficient diversity in feature databases, and the initial parameters of positioning models tend to fall into local optima, leading to significant fluctuations in positioning errors in complex indoor scenarios and making it difficult to consistently achieve high-precision positioning results. Therefore, it is necessary to address the problems of weak signal anti-interference capability, inadequate feature representation, and insufficient model parameter optimization by focusing on three core aspects: data collection, feature extraction, and model optimization, thereby providing a technical pathway to enhance the accuracy and stability of indoor positioning. In this regard, to improve the stability and accuracy of this technology, the design of light source layout and image data acquisition method was studied. This research developed an image data feature extraction method based on Resnet50 and referenced the idea of feature pyramid. Meanwhile, an indoor location sensing model based on Elman network was designed, and an improved grey wolf optimization algorithm was proposed to optimize the initial weights and threshold parameters of the Elman network. The results showed that the average cosine similaritycorresponding to the feature extraction methoddesigned in the studywas 0.103, which wascloser to 0, indicating that the feature library constructed by this method was more diverse. Under different test functions, the average fitness values of the improved grey wolf optimization algorithm were 2.69 × 105, 1.47 × 101, and 2.17 × 102, respectively, all of which were lower than the comparison algorithm. At different heights, the average errors of the designed perception model were 3.04 cm, 3.57 cm, and 3.19 cm, respectively, which were notably lower than the comparison models. The design model also performed better in dynamic analysis and environmental light impact analysis. The designed perception model exhibited excellent performance and is capable of offering technical assistance for improving indoor positioning accuracy.

An empirical, path-oriented approach to software analysis and testing

Special percussive mechanisms have been used to explore the lunar, Martian, and other planetary subsurface and extract soil (regolith)/rock samples for further study. The special type of percussive mechanisms investigated in this study, Auto-Gopher and Ultrasonic/Sonic Driller/Corer (USDC) developed by National Aeronautics and Space Administration (NASA) Jet Propulsion Laboratory and Honeybee Robotics Spacecraft Mechanisms Corporation, consists of an ultrasonic horn, a free mass (hammer), and the drill rod. This paper presents a general methodology to perform the dynamic contact analysis of the longitudinal impact of the free mass on the drill rod including the effects of structural vibration and damping of the rod. The contact force caused by impact is obtained by using Hertz force-indentation relation coupled with the structural vibration of the rod obtained by using mode superposition method and finite-element technique. Numerical solution, with equilibrium iterations, of the equations of motio...

"Change Impact Analysis" is the process of determining the consequences of a modification to software. In theory, change impact analysis should be done during software maintenance, to make sure changes do not introduce new bugs. Many approaches and techniques are proposed to help programmers do change impact analysis automatically. However, it is still an open question whether and how programmers do change impact analysis. In this paper, we conducted two studies, one in-depth study and one breadth study. For the in-depth study, we recorded videos of nine professional programmers repairing two bugs for two hours. For the breadth study, we surveyed 35 professional programmers using an online system. We found that the programmers in our studies did static change impact analysis before they made changes by using IDE navigational functionalities, and they did dynamic change impact analysis after they made changes by running the programs. We also found that they did not use any change impact analysis tools.

Dental trauma is a common emergency in children with primary teeth. The aim of this study was to determine stress propagation to the permanent tooth germ and surrounding bone and soft tissues during dental trauma to primary central incisors with three levels of physiological root resorption. Stresses were determined using finite element analysis (FEA). Cross-sectional models were created using cone-beam computed tomography images of 3.5, 5, and 6years olds, representing three different physiological root resorption stages of a maxillary primary central incisor. The models included periodontal ligament, bone, and soft tissues. An impact with an asphalt block moving at 1m/s,was simulated for two impact two directions, frontal on the labial tooth surface, and on the incisal edge. Stresses and strains were recorded during impact. The impact caused stress concentrations in the surrounding bone and soft tissues and permanent tooth germ, regardless of the direction of impact and the primary tooth resorption stage. Impact stresses in dental follicles and surrounding bone increased in models with more physiological root resorption of the primary tooth. Incisal impact generated higher stress concentrations in surrounding bone and soft tissues and permanent tooth germ regardless of physiological root resorption stage. The primary incisor with no physiological root resorption showed high stress concentrations at its root apex. During impact to a primary incisor, stresses most significant for potential damage to the formation of permanent enamel and dentin were at the dental follicle and surrounding bone tissue with the three levels of physiological root resorption.

Dynamic photoelastic model analysis of impact to the human skull

Impact analysis - determining the potential effects of changes on a software system - plays an important role in software engineering tasks such as maintenance, regression testing, and debugging. In previous work, two new dynamic impact analysis techniques, CoverageImpact and PathImpact, were presented. These techniques perform impact analysis based on data gathered about program behavior relative to specific inputs, such as inputs gathered from field data, operational profile data, or test-suite executions. Due to various characteristics of the algorithms they employ, CoverageImpact and PathImpact are expected to differ in terms of cost and precision; however, there have been no studies to date examining the extent to which such differences may emerge in practice. Since cost-precision tradeoffs may play an important role in technique selection and further research, we wished to examine these tradeoffs. We therefore designed and performed an empirical study, comparing the execution and space costs of the techniques, as well as the precisions of the impact analysis results that they report. This paper presents the results of this study.

The sliding surface algorithms in three-dimensional dynamic finite element code

Impact analysis (IA) is a critical software maintenance task that identifies the effects of a given set of code changes on a larger software project with the intention of avoiding potential adverse effects. IA is a cognitively challenging task that involves reasoning about the abstract relationships between various code constructs. Given its difficulty, researchers have worked to automate IA with approaches that primarily use coupling metrics as a measure of the “connectedness” of different parts of a software project. Many of these coupling metrics rely on static, dynamic, or evolutionary information and are based on heuristics that tend to be brittle, require expensive execution analysis, or large histories of co-changes to accurately estimate impact sets. In this paper, we introduce a novel IA approach, called Athena , that combines a software system’s dependence graph information with a conceptual coupling approach that uses advances in deep representation learning for code without the need for change histories and execution information. Previous IA benchmarks are small, containing less than ten software projects, and suffer from tangled commits, making it difficult to measure accurate results. Therefore, we constructed a large-scale IA benchmark, from 25 open-source software projects, that utilizes fine-grained commit information from bug fixes. On this new benchmark, our best performing approach configuration achieves an mRR, mAP, and HIT@10 score of 60.32%, 35.19%, and 81.48%, respectively. Through various ablations and qualitative analyses, we show that Athena ’s novel combination of program dependence graphs and conceptual coupling information leads it to outperform a simpler baseline by 10.34%, 9.55%, and 11.68% with statistical significance.

This study aims to improve the structural strength and reduce the weight of a full-suspension electric-assisted bike frame using a multi-objective optimization approach. A comprehensive and major design framework is implemented, integrating the uniform design of experiments, Kriging interpolation, entropy weight method, technique for order preference by similarity to an ideal solution (TOPSIS), and a genetic algorithm. Five geometric parameters of the bike frame are selected as control factors in the uniform design. Finite element analysis is conducted to simulate impact displacements under the EN 15194 standard test conditions. Each simulation evaluates frame performance across various parameter combinations. The proposed optimization strategy is validated through falling-mass and falling-frame impact simulations, achieving respective improvements of 4.53% and 5.29% over the original design. Furthermore, the optimized frame demonstrates a weight reduction of 52.51 g. A full factorial design and analysis of variance are employed to identify the most influential parameters, and a comprehensive sensitivity analysis evaluates the relative impact of each factor on the objective functions. These results confirm the effectiveness of the proposed optimization method in producing a stronger and lighter bike frame.

The objectives and procedures of a recently completed joint industry project (JIP) examining jackup behaviour during touchdown are briefly described. Aspects covered include motions analysis, spudcan-soil behaviour, dynamic impact analysis, leg structural capacity and risk calculations. lhese features ha ve been incorporated in an analytical program, GMIMPACT, intended for use on-board jack-ups. The emphasis in this paper is on describing the results of the work as they relate to the limiting seastates applicable to a typical jack-up manoeuvring onto location. The variables which were considered were leg length, wave height and period, touchdown operation duration and seabed type. The paper demonstrates that, by consideration of site specific conditions, the time waiting on weather to move onto or off location can be reduced in a number of circumstances. INTRODUCTION A Joint Industry Project (JIP) has been carried out to investigate the behaviour of jack-ups during touchdown. This work comprised two phases and has been undertaken with the dual aims of increasing safety and of reducing weather downtime. Existing guidance on touchdown is of a very limited nature, the decision as to whether or not to proceed with the operation often being determined by the adoption of a universal limiting significant wave height (typically 5ft). In addition to a comprehensive set of analytical results, the main product of Phase 1 of the JIP [11 has been a computer program which enables the user to specify details on rig type, soil type, water depth and wave height and provides guidance on risk to assist in the decision making process. Output is in the form of a table showing the percentage probability of leg overstress for various wave periods and directions. Phase 2 of the JIP extended the work to examine the safety of jack-ups moving onto location in close proximity to a fixed structure - for example in tender assist or workover modes. This work has considered the likelihood and consequences of an impact between a spudcan and the fixed structure as the rig prepares to touchdown. This paper briefly summarises those aspects of Phase 1 which have already been published [2,31 and then concentrates on explaining the basis for estimating the risks involved in touchdown operations and presents the results of the work. OBJECTIVES AND PROCEDURE In attempting to define a basis for proceeding with touchdown, the main criterion is to ensure that the risk of exceeding the leg structural capacity is not unacceptably high. The approach adopted involved the following aspects:Jack-up motions afloatSeabed-soil characteristicsDynamic impact response (finite element analysis)Leg structural limitationsDetermination of probability of exceedance of allowable leg loads.Development of an analytical computer program, combining all the above aspects and providing estimates of risk.