Excavator 3D pose estimation using deep learning and hybrid datasets

Earthwork operations are crucial parts of most construction projects. Heavy construction equipment and workers are often required to work in limited workspaces simultaneously. Struck-by accidents resulting from poor worker and equipment interactions account for a large proportion of accidents and fatalities on construction sites. The emerging technologies based on computer vision and artificial intelligence offer an opportunity to enhance construction safety through advanced monitoring utilizing site cameras. A crucial pre-requisite to the development of safety monitoring applications is the ability to identify accurately and localize the position of the equipment and its critical components in 3D space. This study proposes a workflow for excavator 3D pose estimation based on deep learning using RGB images. In the proposed workflow, an articulated 3D digital twin of an excavator is used to generate the necessary data for training a 3D pose estimation model. In addition, a method for generating hybrid datasets (simulation and laboratory) for adapting the 3D pose estimation model for various scenarios with different camera parameters is proposed. Evaluations prove the capability of the workflow in estimating the 3D pose of excavators. The study concludes by discussing the limitations and future research opportunities.     

Integrated mathematical optimisation approach for the tower crane hook routing problem to satisfy material demand requests on-site

Optimising decisions around the location and operation of tower cranes can improve the workflow in construction projects. Traditionally, the location and allocation problems involved in tower crane operations in the literature have been solved separately from the assignment of material supply points to demand points and the scheduling of the crane’s activity sequence across supply and demand points on a construction site. To address the gap, this paper proposes a binary integer programming problem, where location of the tower crane, allocation of supply points to material-demanding regions, and routing of hook of the crane based on activity sequencing of the hook across supply and material-demanding regions on site are optimised. The novelty in this work is in the way the crane’s activity scheduling is modelled via mathematical programming, based on routing the hook movement to meet material demand, through minimising tower crane operating costs. A realistic case study is solved to assess the validity of the model. The model is contrasted with results obtained from other solving algorithms commonly adopted in the literature, along with a solution proposed by an experienced practitioner. Results indicate that all instances can be solved when compared to other meta-heuristics that fail to achieve an optimum solution. Compared to the solution proposed by the practitioner, the results of the proposed model achieve a 46% improvement in objective function value. Planners should optimise decisions related to the location of the crane, the crane’s hook movement to meet service requests, and supply points’ locations and assignment to material-demanding regions simultaneously for effective crane operations.     

基于失效分析的软件可靠性评估方法研究

基于用户运行剖面的软件可靠性测试理论广泛地应用在软件测试领域.然而,这种软件可靠性测试既耗时又昂贵.在国内,现在进行的软件黑盒测试主要是系统测试,对于高可靠性要求的软件,系统测试后也需要评估它的可靠性水平.介绍了一种基于失效分析的软件可靠性评估方法,这种方法利用了软件系统测试后得到的缺陷数据,对每一个缺陷导致失效的内外...     

基于xMAS模型的SpaceWire信誉逻辑的形式化验证

空间总线(SpaceWire)协议是应用于航空航天领域的高速通信总线协议, 保证其可靠性至关重要。但是由于通信系统具有队列量、分布控制和并发性等特点,传统仿真模拟的验证方法存在不完备性的问题,采用模型检测方法对高层次属性进行验证时,通常会出现状态爆炸的问题。基于xMAS模型对SpaceWire通信系统中的信誉逻辑进行形式化建模、验证,xMAS模型既保留了底层的结构信息,又可以验证高层次的属性。对通信系统中信誉逻辑进行抽象进而建立了xMAS模型,提取了可发送性、可接收性和数据一致性等3个关键属性,运用定理证明工具ACL2对关键属性的正确性进行了自动验证。该方法为验证指导下的系统设计提供了有效的参考。     

相互依存网络鲁棒性研究综述

对相互依存网络的研究现状进行综述. 介绍了相互依存网络的概念和模型, 并简单描述了相互依存网络上的级联失效过程. 根据网络的拓扑结构, 分别从一对一连接关系的相互依存网, 多对多连接关系的相互依存网, 多层网络系统以及无标度网络构成的相互依存网络四个部分介绍相互依存网的鲁棒性研究, 及其鲁棒性的提升方法. 最后对相互依存网络的研究现状进行小结并对未来发展做出展望.     

测试性验证技术与应用现状分析

阐述了测试性验证技术在新型装备PHM设计中的重要性,分析了测试性验证相关的国内外军用标准,归纳了相关军用标准在适用性方面存在的不足之处,指出应该建立测试性验证专用标准指导测试性验证工作。调研了国内测试性验证技术的应用情况,从测试性试验和测试性评估验证两个方面分析了测试性验证技术在实际应用中遇到的问题,并进一步确定了测试性验证标准中应该提供的内容,为测试性验证技术研究和标准的制定奠定了良好的基础。     

Diagnosis of a soft short and local variations of parameters occurring simultaneously in analog CMOS circuits

This paper is devoted to fault diagnosis of nonlinear analog CMOS circuits designed in nanometer technology. A method that allows diagnosing a single soft short and local parameter variations, occurring simultaneously, is developed. The method exploits DC measurements at limited number of points in the test phase. The diagnostic test leads to a system of nonlinear algebraic equations, not given in explicit analytical form, that may have multiple solutions. The solutions determine the sets comprising one soft short value and several values of the preliminary selected parameters. To find them an extended simplicial algorithm is developed. It allows tracing different space curves, leading to different solutions. Moreover, a procedure for selecting the actual solution from among the obtained ones is proposed. For illustration a representative numerical example is discussed in detail.     

Perturbed dynamics of discrete-time switched nonlinear systems with delays and uncertainties

This paper addresses the dynamics of a class of discrete-time switched nonlinear systems with time-varying delays and uncertainties and subject to perturbations. It is assumed that the nominal switched nonlinear system is robustly uniformly exponentially stable. It is revealed that there exists a maximal Lipschitz constant, if perturbation satisfies a Lipschitz condition with any Lipschitz constant less than the maximum, then the perturbed system can preserve the stability property of the nominal system. In situations where the perturbations are known, it is proved that there exists an upper bound of coefficient such that the perturbed system remains exponentially stable provided that the perturbation is scaled by any coefficient bounded by the upper bound. A numerical example is provided to illustrate the proposed theoretical results.     

Determination of the critical plane by a weight-function method based on the maximum shear stress plane under multiaxial high-cycle loading

A weight function method for the determination of the critical plane is here proposed for the case of specimens under combined bending and torsion in the high cycle fatigue regime. The critical plane is assumed to be coincident with the mean maximum absolute shear stress plane, which is calculated by averaging the instantaneous angle between the specimen axis and the normal to the maximum absolute shear stress plane. Two kinds of weight functions are proposed to determine such a plane. The proposed method to determine the critical plane is verified by employing fatigue data available in the literature in terms of experimental fracture planes, and the multiaxial fatigue life is also predicted by a reformulation of the criterion proposed by Carpinteri et al. to verify the determined critical plane. The results show that the proposed method can be applied to determine the critical plane under both constant and variable amplitude loading.     

In-situ investigation of EMC relaxation behavior using piezoresistive stress sensor

The relaxation behavior of an epoxy molding compound (EMC) subjected to a constant strain can cause new reliability challenges in automotive electronics. This problem will be exacerbated due to the ever-increasing demand in modern electronics systems for miniaturization with more functionality, yet it has not been studied extensively to mitigate its effect on reliability. In this study, a piezoresistive silicon-based stress sensor is used to understand the stress state in an electronic control unit (ECU), more specifically the relaxation behavior of EMC caused by the storage time of an ECU (i.e., duration between production and actual usage). Mechanical stresses are measured by the piezoresistive stress sensor that is encapsulated in a standard microelectronic 3 × 3 mm land grid array (LGA) package. The relaxation behavior is observed at three different temperatures for 1 week: 75 °C, 100 °C and 125 °C. The relaxation behavior is measured continuously for one more week after cooling the package to room temperature (at 25 °C). An additional test is conducted at 85 °C with 85% relative humidity to investigate the effect of moisture diffusion on the package. The experimental results clearly indicate that the proposed approach can be used for better understanding of the evolution of stresses in molded packages during their lifetime, especially during storage, which in turn can lead to more optimal designs in the future.