Ergonomics aspects of knob designs: a literature review

Hand-related apparatus designs that fail to accommodate appropriate hand postures can cause hand-related musculoskeletal disorders. While there have been studies on the handling and design of various hand-related apparatus, little has been written on the ergonomics aspects of knob designs. The aim of this paper is to review various knob designs and their ergonomics aspects. The literature review suggests that gearshift knobs, door knobs, gas valve knobs, butterfly nuts and screw knobs are common knobs used for daily living activities. Other knobs like the convex, knurled, spherical, cone-shaped and ridged knob are often used for industrial-related applications. The ergonomics considerations identified in knobs include aesthetic attraction, position, torque requirement and shape-coding. This literature review can be used as groundwork for the development of ergonomics theory and hand-related studies. Engineers can use this literature review to identify certain ergonomics aspects in knobs to improve equipment designs, operating efficiency and working comfort.     

A review of shape and size considerations in pinch grips

In handgrip-related studies, it has been theorised that modifying the design of object shapes and sizes to accommodate the hand can reduce risks of cumulative trauma disorders (CTDs). However, there appears to be a lack of theoretical groundwork to support this premise in the area of pinch grip research. Therefore, this article aims to provide a review of shape and size considerations in pinch grips. The literature reviews were first conducted individually on shape, size and pinch grip factors, followed by the development of a literature summary based on the theoretical connections among shape, size and pinch grips. Though further studies are still required, this review has provided fundamental knowledge on possible theoretical connections among shape, size and pinch grip factors. These preliminary efforts shed light on potential mechanisms that explain how shape and size can influence pinch grips towards preventing CTDs and maximising the human performance.     

Optimization of soy-biodiesel combustion in a modern diesel engine

As global petroleum demand continues to increase, alternative fuel vehicles are becoming the focus of increasing attention. Biodiesel has emerged as an attractive alternative fuel option due to its domestic availability from renewable sources, its relative physical and chemical similarities to conventional diesel fuel, and its miscibility with conventional diesel. Biodiesel combustion in modern diesel engines does, however, generally result in higher fuel consumption and nitrogen oxide (NO_x) emissions compared to diesel combustion due to fuel property differences including calorific value and oxygen content. The purpose of this study is to determine the optimal engine decision-making for 100% soy-based biodiesel to accommodate fuel property differences via modulation of air-fuel ratio (AFR), exhaust gas recirculation (EGR) fraction, fuel rail pressure, and start of main fuel injection pulse at over 150 different random combinations, each at four very different operating locations. Applying the nominal diesel settings to biodiesel combustion resulted in increases in NO_x at three of the four locations (up to 44%) and fuel consumption (11-20%) over the nominal diesel levels accompanied by substantial reductions in particulate matter (over 80%). The biodiesel optimal settings were defined as the parameter settings that produced comparable or lower NO_x, particulate matter (PM), and peak rate of change of in-cylinder pressure (peak dP/dt, a metric for noise) with respect to nominal diesel levels, while minimizing brake specific fuel consumption (BSFC). At most of the operating locations, the optimal engine decision-making was clearly shifted to lower AFRs and higher EGR fractions in order to reduce the observed increases in NO_x at the nominal settings, and to more advanced timings in order to mitigate the observed increases in fuel consumption at the nominal settings. These optimal parameter combinations for biodiesel were able to reduce NO_x and noise levels below nominal diesel levels while largely maintaining the substantial PM reductions. These parameter combinations, however, had little (maximum 4% reduction) or no net impact on reducing the biodiesel fuel consumption penalty.     

Explosive Detection by Microthermal Analysis

Differential scanning microcalorimetry at high heating rates of ～ 300°C/s was performed on 30- to 100-µm-size explosive particles using two MEMS-based thermal conductivity gauges in air and under N₂. The gauges consist of a thin-film Si₃N_x membrane with a centrally located Al thin-film heater, which is surrounded by six thin-film Si/Al junctions, creating a temperature-sensitive thermopile (～ 1.3 mV/K) with an effective sensitive area of ca. 200 × 200 µm. Heating was carried out by applying a linear voltage ramp during 1.6 s. The measurements were performed in a specially designed exposure chamber having a transparent glass lid that enabled optical observation of the thermal process.

Besides explosives (TNT, RDX, picric acid, urea nitrate, and TATP) we have studied nonexplosive materials, organic and inorganic, in order to see whether the explosives have a unique response. The materials we studied were oxygen-poor and -rich organic compounds (polyethylene and sugars, respectively), sea sand, and iron flakes.

Clear, well-resolved exotherms were obtained at moderated temperatures (～ 250°C) for all types of explosive materials tested by us. In addition, all explosives exhibited a melting endotherm preceding the exotherm. Sea sand and iron showed no peaks at the heating temperature range. Polyethylene showed an endotherm representing its melting. The sugars showed an endotherm but also an exotherm when heated to elevated temperatures (> 370°C). The thermogram of each material depends on its properties and is characterized by a unique pattern. This pattern may enable the detection and identification of explosive particles using this technology.     

Number-theoretic functions which are equivalent to number of divisors

Let d(n) denote the number of positive integral divisors of n. In this paper we show that the Möbius function, μ(N), can be computed by a single call to an oracle for d(n). We also show that any function that depends solely on the exponents in the prime factorization of N can be computed by at most log₂ N calls to an oracle for d(N).     

IGC study of surface properties of adsorbed styrene/methacrylic acid diblock polymers

An inverse gas chromatographic study has been carried out on a styrene/methacrylic acid diblock polymer adsorbed on particulates of varying acid/base interaction potential. Acid/base interactions between polymer and substrate were shown to result in the selective adsorption of copolymer moieties, leading to interphase surface compositions that varied with thickness. At higher interphase thicknesses, bulk and surface compositions became similar; however, depending on the interaction potential of the adsorbent, the interphase thicknesses at this point varied from 100 to 1000 Å. Adsorbed diblock interphases are to be considered nonisotropic in local composition and molecular conformation. These properties may make possible designing diblock interphases to meet specific compatibilization requirements in polymer composites. © 1994 John Wiley & Sons, Inc.     

移动式小型X线机综合防护装置

本文介绍一种移动式小型 X 线机综合防护装置。该装置把便于运输的部件、防护隔屏及暗室融为一体,为 X 线工作者、被检者和被检者提供了较好的防护。本文介绍一种移动式小型 X 线机综合防护装置。现将其基本构造和防护效果简介如下:     

Miscibility of polyamide-6 and polystyrene functionalized with sulfonic acid groups

Polyamide-6 (PA-6) and sulfonated polystyrene (SPS) interact strongly in solution. Thus, solution blends of PA-6 and SPS (sulfonation levels from 0 to 12.3 mol%) in m-cresol form clear, hazy, or gelled solutions–depending on the ratio of amide (A) to sulfonic acid (S) groups (A/S). NMR studies show that the S groups interact with the nitrogen of the amides, most probably through the transfer of the sulfonic acid protons. During melt blending, the addition of SPS to the PA-6 leads to a torque rise because of strong interactions. The glass transition temperatures of the components in the melt blended samples shift towards each other as the sulfonation level of the SPS increases, indicating enhanced miscibility. The analysis of the extracted PA-6 from thee blends, however, shows that it is degraded at processing temperatures (250°C), owing to some residual water and the catalytic activity of the sulfonic acid groups. The extent of the PA-6 degradation is inversely related to the A/S ratio. Each sulfonic acid group causes between one and two chain scissions of the PA-6. In blends with high A/S ratios, the degradation of the PA-6 is minimal; yet considerable dispersion of the SPS can be achieved, as evidenced by scanning electron micrographs of the fracture surfaces.     

Blends of polyurethane carboxylates with styrene vinylpyridinium copolymers

This is a continuation of an ongoing investigation of miscibility enhancement via ionic interactions in urethane-styrene blends. The present study deals with a polyurethane which contains in the hard segments pendant carboxylate groups neutralized by ammonium ions while the polystyrene contains pendant vinyl pyridinium methyl iodide groups. Miscibility of the styrene is seen with the hard segments of the urethane because of ion pair/ion pair interactions. Methanol extraction raises the T_g because it eliminates low molecular weight components, without removing the microions.     

An efficient phishing webpage detector

Phishing attack is growing significantly each year and is considered as one of the most dangerous threats in the Internet which may cause people to lose confidence in e-commerce. In this paper, we present a heuristic method to determine whether a webpage is a legitimate or a phishing page. This scheme could detect new phishing pages which black list based anti-phishing tools could not. We first convert a web page into 12 features which are well selected based on the existing normal and fishing pages. A training set of web pages including normal and fishing pages are then input for a support vector machine to do training. A testing set is finally fed into the trained model to do the testing. Compared to the existing methods, the experimental results show that the proposed phishing detector can achieve the high accuracy rate with relatively low false positive and low false negative rates.