Minimizing the average tardiness: the case of outsource machines

Two important factors that affect outsourcing decisions are the production cost and the potential loss of customer goodwill due to late orders. This article deals with the problem of finding outsourcing strategies or solutions that consider trade-offs between outsourcing cost and average tardiness, an important measure of lost customer goodwill. Assumptions include that outsource costs are a function of machine use and that the planning organization owns no production equipment; instead, the production function is completely outsourced. Furthermore, the planning organization has flexibility in terms of the quantity of parallel production resources to outsource and it controls the assignment of jobs to these parallel production resources. The article presents lower bounds for the problem, which are used for comparisons. Several approaches to generate trade-off solutions are proposed and compared under a variety of experimental factors.     

Examination of the causes of a bucket wheel fracture in a bucket wheel excavator

A bucket wheel excavator failure occurred in a brown-coal mine. The failure was caused by a fractured shaft of the bucket wheel. An attempt to determine the causes of the bucket wheel shaft fracture has been made. To that end, the character of changing loads and their maximum amplitudes has been determined by performing measurements on the excavator. A discreet model of the shaft was built and a numerical simulation of the shaft operation using the FEM method was achieved. An analysis of the materials in the fracture area was also implemented. Macroscopic and microscopic images of the fracture area are provided. The shaft fracture was mainly caused by a non-metallic inclusion located below the surface of the shaft as a result of its being rolled. Moreover, it was discovered that the shaft had not been heat-treated.     

机器噪声的谱相关

文章以风扇噪声为例分析了影响机器噪声谱相关的一些因素，为利用机器噪声的谱相关来诊断机器发生故障，供选取调味品阈时提供参考。     

Hydrogel machines

As polymer networks infiltrated with water, hydrogels constitute the major components of the human body; and hydrogels have been widely used in applications that closely interact with biological organisms, such as tissue engineering, drug delivery, and biological research. More recently, owing to their superior softness, wetness, responsiveness, biocompatibility, and bioactivity, hydrogels are being intensively investigated for versatile functions in devices and machines including sensors, actuators, coatings, optics, electronics, and water harvesters. A nascent field named hydrogel machines rapidly evolves, exploiting hydrogels as key components for devices and machines. While there are reviews on individual categories of hydrogel machines in literature, a comprehensive discussion on various categories of hydrogel machines that systematically correlate hydrogels’ properties and machines’ functions is still missing in the field. This review is aimed to provide such a panoramic overview. We first classify various hydrogel machines into a number of categories according to their applications. For each category, we discuss (i) the working principles of the hydrogel machines, (ii) the specific properties of hydrogels that enable the key functions of the machines, and (iii) challenges faced by hydrogel machines and recent developments to address them. The field of hydrogel machines will not only translate fundamental understanding of hydrogels into new applications, but also shift the paradigm in machine design by integrating hydrogels that can potentially minimize physical and physiological mismatches with biological organisms.     

Men and machines: The computational metaphor

In the 20th century the interpretation of the human mind and brain as a computer has replaced the 18th century metaphor of “man as a machine”. This paper traces the development of the computational metaphor with some attention to its 18th century roots, and then argues that its employment need not lead to the mechanization of thinking and the autonomy of technique. An awareness of the metaphoric and, therefore, hypothetical status of the computational metaphor will prevent technique from escaping intentional human control. This is a shortened version of a paper included in C. Mitcham and Alois Huning, eds., Philosophy and Technology II: Information Technology and Computers in Theory and Practice (Boston: D. Reidel, in press), and is included here with permission.     

DNA machines: bipedal walker and stepper

The assembly of a "bipedal walker" and of a "bipedal stepper" using DNA constructs is described. These DNA machines are activated by H(+)/OH(-) and Hg(2+)/cysteine triggers. The bipedal walker is activated on a DNA template consisting of four nucleic acid footholds. The forward "walking" of the DNA on the template track is activated by Hg(2+) ions and H(+) ions, respectively, using the thymine-Hg(2+)-thymine complex or the i-motif structure as the DNA translocation driving forces. The backward "walking" is activated by OH(-) ions and cysteine, triggers that destroy the i-motif or thymine-Hg(2+)-thymine complexes. Similarly, the "bipedal stepper" is activated on a circular DNA template consisting of four tethered footholds. With the Hg(2+)/cysteine and H(+)/OH(-) triggers, clockwise or anticlockwise stepping is demonstrated. The operation of the DNA machines is followed optically by the appropriate labeling of the walker-foothold components with the respective fluorophores/quenchers units.     

The use of bearing elements in the structure of superabrasive wheel working layer to improve the wheel performance

A study is performed to find ways for efficient use of bearing elements in the form of layered compacts or milled Kiborite in the working layer of superabrasive wheels in order to improve the wheel performance in grinding processes.     

The restless mind while driving: drivers’ thoughts behind the wheel

Recent research has clearly shown that inattention when driving has an indisputable impact on road safety. “Mind wandering” (MW), an inattentional state caused by a shift in attention from the ongoing task to inner thoughts, is not only frequent in everyday activities but also known to impact performance. There is a growing body of research investigating the concept of MW, suggesting potential causes that could foster such a phenomenon. Only one epidemiological study has focused on this issue in a critical driving context ( Galéra et al., 2012), and it revealed the harmful effects of MW in increasing the risk of a car crash. Experimental studies rather consider that driver would adduce in MW ( Lemercier et al., 2014). When the driving context is too hard or the thought too difficult to proceed, driver reduced their MW. The aim of this paper is to examine this issue using the most recent trip of ordinary drivers whose MW state did not lead to a road accident. Using a questionnaire, information was collected about the participants’ most recent trip as a driver, including: (1) personal characteristics, (2) context in which MW occurs, (3) awareness of MW episodes and finally (4) characteristics of the thoughts.     

Failure of the bucket wheel excavator buckets

Buckets are a vital substructure of all digging machines, and are intended for the realisation of the fundamental machine function - soil excavation. This paper presents the results of the experimental-numerical investigation of the cause of the bucket wheel excavator SRs 470 buckets failure. The chemical composition and mechanical properties, the impact toughness, hardness, tendency to cracks and the microstructure were determined using appropriate tests. Experimental examinations of working and residual stresses were performed using strain gauges. The superposition of the experimentally determined working and residual stresses and the calculation of the total principal stresses were conducted using the originally developed procedure presented in this paper. The bucket working stress state was calculated by applying the linear finite element method. Conclusions based on the investigation results show that the main reasons for the buckets failure were the ‘design-in defects’ - oversights made during the procedures of geometrical shaping and material selection. Furthermore, high values of residual stresses, as well as the cold cracking observed on the welded joint of the knife and the bucket body, suggest that the ‘manufacturing-in defects’ also played a significant role in the failure. The superposition of influences of the ‘design-in defects’ and the ‘manufacturing-in defects’ has conditioned the appearance and propagation of long-term fatigue cracks, leading to the total destruction of the buckets. The fact that buckets' failure appeared due to oversights made during geometrical shaping, material selection and manufacturing further points to the importance of the critical approach implementation during the design phase of the earthmoving machines working devices.     

Testing the precision of metal-working machines

Measurement Techniques -     

列车车轮踏面剥离机理研究

本文分析讨论了列车车轮踏面剥离现象的形成机理，通过模拟轮轨各种接触式试验的方法分析了列车制动状况及其与轮轨摩擦力之间的联系。并针对我国铁路的具体情况分析了车轮踏面剥离在我国的成因。     

Superconducting rotating machines

The opportunities and limitations of the applications of superconductors in rotating electric machines are given. The relevant properties of superconductors and the fundamental requirements for rotating electric machines are discussed. The current state-of-the-art of superconducting machines is reviewed. Key problems, future developments and the long range potential of superconducting machines are assessed.