Pistol shooting accuracy as dependent on experience, eyes being opened and available viewing time

A study of the shooting accuracy of three groups of pistol shooters is reported. The groups included (i) experienced gas pistol shooters; (ii) persons with experience in video shooting games; and (iii) persons with no shooting experience. The viewing time was varied in the tests. The results showed that experience had a significant effect on the mean and root mean square (RMS) shooting errors at the target. The results also showed that the viewing time does not need to exceed about 2 s for an experienced pistol shooter and about 3 s for a novice shooter to reach the best performance. Two models for the effects of limited viewing time are proposed; both models fit the data well when the viewing time is less than about 2 s. The results indicated that the differences occurring with varying levels of experience are due to postural balance and not due to the aiming or cognitive component of the task.     

A constrained recursive pseudo-linear regression scheme for on-line parameter estimation in adaptive control

In adaptive control of systems with poles close to the unit circle, application of the recursive estimation techniques can lead to excursions of the poles of the identified model outside the unit circle even when the process is open loop stable. These excursions can be of two types. The poles of the deterministic component of the model can drift outside unit circle even when the process has no unstable modes. Alternatively, the poles and/or zeros of the unmeasured disturbance (noise) model can drift outside the unit circle. In either case, the identified model is not suitable for on-line controller adaptation. In this work, a novel constrained recursive formulation is proposed for on-line parameter estimation based on the pseudo-linear regression (PLR) approach. The efficacy of the proposed approach is demonstrated by conducting experimental studies on a benchmark laboratory scale heater-mixer setup. The analysis of the open and closed loop experimental results reveals that the proposed constrained parameter estimation scheme provides a systematic and computationally attractive approach to ensure that the identified model parameters are restricted to the feasible region.     

A qualitative study on the comfort and fit of ladies' dress shoes

The perceived differences between comfortable and uncomfortable shoes and the fit preferences in the different regions of ladies' shoes were explored. Twenty Hong Kong Chinese females participated in the study. Each participant wore and rated the different aspects of their own comfortable and uncomfortable shoes. The Wilcoxon signed rank tests showed significant differences in ten perceived characteristics between the comfortable and uncomfortable shoes. Among the ten were tactile, auditory and olfactory sensations. The ten items reliably (Cronbach alpha>0.9) distinguished between comfortable and uncomfortable shoes. There were no significant differences between comfortable and uncomfortable shoes for aesthetic-related characteristics. Further analysis on the fit ratings showed a significant impact on the fit preferences in the Toe region (p<0.0001), Metatarsophalangeal (MPJ) region (p<0.0001), Arch region (p=0.002) and Ingress/egress opening (p<0.001). Knowing the preferred type of fit can help establish a specification for comfortable shoes and also brings out the criteria that a comfortable shoe does not necessarily have the same perceived fit in every region of a shoe.     

The Effect of a Web-Based Tutorial on Problem Formulation Ability

Business programs are under greater pressure than ever to provide their students with the analytical skills they will need for effective problem solving. The increasing complexity of today's business environment and the expanding volume of data to support decision making require students to have better modeling skills. Tutorials can shape and enhance skill development in domains which are process intensive and contain problems where mastery and proficiency require practice. In this paper, we present a web-based tutorial, MS-Tutor, to coach students on all aspects of algebraic formulation of linear and integer programs. Such tutorials have the potential to become an integral component of web-based course offerings. However, it is important to design the content in such a way that it enhances the learning process. MS-Tutor was designed by considering the following dimensions: Structure, which refers to the organization of the content; Feedback, so students can learn from mistakes; and Dialog, which affects the interaction between the user and the tutor. The results indicate there is potential for performance improvement if the tutor is used.     

Does information security attack frequency increase with vulnerability disclosure? An empirical analysis

Research in information security, risk management and investment has grown in importance over the last few years. However, without reliable estimates on attack probabilities, risk management is difficult to do in practice. Using a novel data set, we provide estimates on attack propensity and how it changes with disclosure and patching of vulnerabilities. Disclosure of software vulnerability has been controversial. On one hand are those who propose full and instant disclosure whether the patch is available or not and on the other hand are those who argue for limited or no disclosure. Which of the two policies is socially optimal depends critically on how attack frequency changes with disclosure and patching. In this paper, we empirically explore the impact of vulnerability information disclosure and availability of patches on attacks targeting the vulnerability. Our results suggest that on an average both secret (non-published) and published (published and not patched) vulnerabilities attract fewer attacks than patched (published and patched) vulnerabilities. When we control for time since publication and patches, we find that patching an already known vulnerability decreases the number of attacks, although attacks gradually increase with time after patch release. Patching an unknown vulnerability, however, causes a spike in attacks, which then gradually decline after patch release. Attacks on secret vulnerabilities slowly increase with time until the vulnerability is published and then attacks rapidly decrease with time after publication.

Sol-gel derived la modified PZT thin films: structure and properties

Lanthanum modified PZT thin films with compositions, namely 8/60/40, 8/70/30, 10/70/30 and 12/70/30 were deposited on platinized silicon substrates by sol-gel spin coating technique. Characterization of these films by XRD and SEM show that the films possess perovskite phase with submicron crystallite size. The saturation polarization (Ps), remnant polarization (PR) and coercive field (Ec) of polarization-electric field hysteresis loop are presented for all compositions. The 8/60/40 composition shows hysteresis loop with P/sub R/ = 11 /spl mu/C/cm/sup 2/. The temperature dependence of dielectric constant and dielectric loss of these films are also studied. Leakage current densities for these thin films are found to be in the range of 10/sup -/-10/sup -/ A/cm/sup 2/. To show the possible application of these thin films for micro electromechanical system (MEMS), a device incorporating an 8/60/40 PLZT thin film has been fabricated using silicon micromachining technology. This device functions satisfactorily as a vibration sensor with a resonance frequency of approximately 8.45 MHz.     

Model based foot shape classification using 2D foot outlines

This study introduces a novel technique to identify foot outline characteristics and to classify feet into groups using turning functions and clustering techniques so that shape can complement anthropometry in producing good fitting shoes. The digital 3D foot scans, obtained from 50 Hong Kong Chinese subjects (25 males and 25 females) were processed to generate the foot outlines at heights of 2 mm and 40 mm. The outlines were represented as turning functions and the similarity among shapes was determined using average linkage clustering. The results show that there are two distinct shape groups for the 40 mm foot outlines on both medial and lateral sides of the foot. The presence (46%) or absence (54%) of a medial bulge characterizes the medial side, while the two shape groups on the lateral side are mainly due to the lateral concavity in the mid-foot region. The group with a lateral concavity consists of more females (68%) and thus lateral side of foot outline appears to be gender related. Furthermore, the medial and lateral side clusters are not related to each other. The medial side shape from the 2 mm foot outline is a good indicator of fallen arches. Based on the analyses, four types of feet were identified: feet with (1) lateral concavity and a medial bulge, (2) a medial bulge and no lateral concavity, (3) lateral concavity and no medial bulge and (4) lateral concavity and a medial bulge. These shape differences can be useful in the design of shoe lasts and in the manufacture of compatible footwear so that trial and error fitting can be minimized.     

Which sort orders are interesting?

Sort orders play an important role in query evaluation. Algorithms that rely on sorting are widely used to implement joins, grouping, duplicate elimination and other set operations. The notion of interesting orders has allowed query optimizers to consider plans that could be locally sub-optimal, but produce ordered output beneficial for other operators, and thus be part of a globally optimal plan. However, the number of interesting orders for most operators is factorial in the number of attributes involved. Optimizer implementations use heuristics to prune the number of interesting orders, but the quality of the heuristics is unclear. Increasingly complex decision support queries and increasing use of query-covering indices, which provide multiple alternative sort orders for relations, motivate us to better address the problem of choosing interesting orders. We show that even a simplified version of the problem is NP-hard and provide a 1/2-benefit approximation algorithm for a special case of the problem. We then present principled heuristics for the general case of choosing interesting orders. We have implemented the proposed techniques in a Volcano-style cost-based optimizer, and our performance study shows significant improvements in estimated cost. We also executed our plans on a widely used commercial database system, and on PostgreSQL, and found that actual execution times for our plans were significantly better than for plans generated by those systems in several cases.     

Superior electrical,mechanical and viscoelastic properties of CNTs coated carbon textile reinforced phenolic composite for high-performance structural applications

In the present study, carbon nanotubes (CNTs) were grown up on nickel-coated carbon textiles utilizing acetylene gas as a carbon precursor in an isothermal CVD reactor. The effects of CNT coating time (0 to 25 min) in the carbon textile-phenolic composites (CPCs) prepared via conventional hand-layup technique followed by compression molding were assessed using microstructures, static and dynamic mechanical thermal analysis, density and electrical properties. Significant improvement was observed in static as well as dynamic mechanical properties and electrical properties for all the CNT coated samples. Though, 15 min coating time gives the optimum results. The results showed ~71, 74, 62, 67, 38, and 45% increment in storage modulus, loss modulus, flexural strength, flexural modulus, tensile strength, Young's modulus, respectively. Furthermore, huge improvement (707%) in electrical conductivity and significant enrichment in thermal stability mark CNTs coated carbon textile as the efficient alternative reinforcement for high-performance thermo-structural applications such as aerospace and automotive fields.     

A qualitative evaluation of water and monomethyl hydrazine in ethylcellulose membrane

Specific interaction sites of ethylcellulose (EC) with water and monomethyl hydrazine (MMH) and its hydrate have been studied by Fourier transform infrared spectra. Measurements of diffusion and sorption coefficients of MMH and water in EC were made from the reduced sorption curves to determine the overall selectivity of the membrane. Flow patterns across the membrane were examined under an optical microscope (OM) equipped with a differential interference contrast (DIC) facility. Correlation of the front velocity and the diffusivity has been used to calculate and compare these values of diffusion coefficient with that obtained from reduced sorption curve. Desorption of MMH hydrate from EC has been attributed to polymer relaxation phenomena. The physical aging process of the membrane has been monitored by FTIR analysis and mechanical strength evaluation. These studies showed that the EC membrane can be used for prolonged periods in MMH and, as such, is suitable for the separation of MMH–water solutions. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 689–700, 1999