The physics of e-commerce supply chains

The Internet is rapidly improving our ability to support information flows across global supply chains. However, the business impact of these IT investments depends not just on the information flows supported by such systems, but also on other non-information related characteristics of the supply chain. It is the complex interplay among these characteristics that results in business performance, or lack thereof. In order to better understand the business impact of IT investments in the supply chain, we are motivated to examine the ‘physics’ of supply chain structures. By physics, we mean the performance patterns inherent in its informational and physical characteristics. Using the systems dynamics methodology, we model basic information and physical characteristics of supply chains and examine their impact on some common measures of performance. Experiments with the models suggest that, in addition to information delays, physical delays also have a major impact on the stability of supply chains, as well as on operating cost. Moreover, the tradeoff between chain stability and responsiveness appears to be nonlinear, suggesting that a small compromise in responsiveness may yield larger gains in stability. Multi-tier chains appear to be less ‘stiff’ in responding to demand fluctuations, implying that their information systems must be specifically designed to overcome this structural tendency. These results have managerial implications in terms of designing the information and physical structure of a supply chain as well as for its operation.     

Patient safety and computerized medication ordering at Brigham and Women's Hospital

BACKGROUND: Medications are important therapeutic tools in health care, yet creating safe medication processes is challenging for many reasons. Computerized physician order entry (CPOE), one important way that technology can be used to improve the medication process, has been in place at Brigham and Women's Hospital (BWH; Boston) since 1993. CPOE AT BWH: The CPOE application, designed and developed internally by the BWH information systems team, allows physicians and other clinicians to enter all patient orders into the computer. Physicians enter 85% of orders, with the remainder entered electronically by other clinicians. CPOE AND SAFE MEDICATION USE: The CPOE application at BWH includes several features designed to improve medication safety--structural features (for example, required fields, use of pick lists), enhanced workflow features (order sets, standard scales for insulin and potassium), alerts and reminders (drug-drug and drug-allergy interaction checking), and adjunct features (the pharmacy system, access to online reference information). RESULTS AT BWH: Studies of the impact of CPOE on physician decision making and patient safety at BWH include assessment of CPOE's impact on the serious medication error and the preventable adverse drug event rate, the impact of computer guidelines on the use of vancomycin, the impact of guidelines on the use of heparin in patients at bed rest, and the impact of dosing suggestions on excessive dosing. CONCLUSION: CPOE and several forms of clinical decision support targeted at increasing patient safety have substantially decreased the frequency of serious medication errors and have had an even bigger impact on the overall medication error rate.     

Person tracking and reidentification: Introducing Panoramic Appearance Map (PAM) for feature representation

This paper develops a concept of Panoramic Appearance Map (PAM) for performing person reidentification in a multi-camera setup. Each person is tracked in multiple cameras and the position on the floor plan is determined using triangulation. Using the geometry of the cameras and the person location, a panoramic map centered at the person’s location is created with the horizontal axis representing the azimuth angle and vertical axis representing the height. Each pixel in the map image gets color information from the cameras which can observe it. The maps between different tracks are compared using a distance measure based on weighted SSD in order to select the best match. Temporalintegration by registering multiple maps over the tracking period improves the matching performance. Experimental results of matching persons between two camera sets show the effectiveness of the approach. This work has been sponsored by the Technical Support Working Group (TSWG) of US Department of Defence (DoD).     

Fabrication of Integrated Vertical Mirror Surfaces and Transparent Window for Packaging MEMS Devices

A scheme for creating metal-coated vertical mirrors in silicon, along with an integrated transparent package lid for assembling, packaging, and testing microelectromechanical systems (MEMS) devices is presented. Deep reaction ion etching (DRIE) method described here reduces the loading effect and maintains a uniform etch rate resulting in highly vertical structures. A novel self-masking lithography and liftoff process was developed to ensure that the vertical mirrors undergo uniform metallization while leaving a transparent window for optical probing. Front side of a Si wafer was shallow-etched using DRIE to define an eventual optical window. This surface was then anodically bonded to a Pyrex wafer. Backside Si was then patterned to define thin channels around the optical window. These channels were vertically etched using DRIE, after which the unattached portions of the window region were removed. Negative photoresist was spun on the remaining vertical structures and the stack was exposed from the Pyrex side using Si structures as a self-mask. Subsequent metal sputtering and liftoff results in the metallized top and mirror sidewalls while leaving a clear window. These integrated mirrors and lids are then bonded to the active MEMS mirrors. Various processes and results are illustrated with an example of packaged corner cube retroreflectors (CCRs)     

Behavior of Stone Columns Based on Experimental and FEM Analysis

A detailed experimental study on behavior of single column and group of seven columns is carried out by varying parameters like spacing between the columns, shear strength of soft clay, and loading condition. Laboratory tests are carried out on a column of 100?mm diameter surrounded by soft clay of different consistency. The tests are carried out either with an entire equivalent area loaded to estimate the stiffness of improved ground or only a column loaded to estimate the limiting axial capacity. During the group experiments, the actual stress on column and clay were measured by fixing pressure cells in the loading plate. Finite-element analyses have also been performed using 15-noded triangular elements with the software package PLAXIS. A drained analysis was carried out using Mohr-Coulomb’s criterion for soft clay, stones, and sand. The numerical results from the FEM are compared with the experimental results which showed good agreement between the results. Columns arranged with spacings more than 3 times the diameter of the column does not give any significant improvement. Based on the results, design charts are developed and a design procedure is suggested.     

MULTIROBOT MOTION PLANNING USING HYBRID MNHS AND GENETIC ALGORITHMS

Planning the motion of multiple robots deals with computing the motion of all robots avoiding any collision. This article focuses on the use of hybrid Multi Neuron Heuristic Search (MNHS) and Genetic Algorithm (GA). The MNHS is an advancement over the conventional A* algorithm and is better suited for maze-like conditions where there is a high degree of uncertainty. The MNHS contributes toward optimality of the solution, and the GA gives it an iterative nature and enables the approach to be used on high-resolution maps. MNHS works over the set of points returned by the GA in its fitness function evaluation. A priority-based approach is used, in which the priorities are decided by the GA. Path feasibility is speeded up by using the concept of coarser-to-finer lookup called momentum. Experimental results show that the combined approach is able to easily solve the problem for a variety of scenarios.

[Supplementary materials are available for this article. Go to the publisher's online edition of Applied Artificial Intelligence for the following free supplemental resource(s): Videos 1-4]     

Majorisations for the eigenvectors of graph-adjacency matrices

We develop majorisation results that characterise changes in eigenvector components of a graph's adjacency matrix when its topology is changed. Specifically, for general (weighted, directed) graphs, we characterise changes in dominant eigenvector components for single- and multi-row incrementations. We also show that topology changes can be tailored to set ratios between the components of the dominant eigenvector. For more limited graph classes (specifically, undirected, and reversibly-structured ones), majorisations for components of the subdominant and other eigenvectors upon graph modifications are also obtained.     

Growth and viability of commercial Bifidobacterium spp. in honey-sweetened skim milk.

Two commercial Bifidobacterium bifidum (Bf-1 and Bf-6) were cultured in 12% (wt/vol) reconstituted nonfat dry milk (NDM) containing 5% (wt/wt) honey, sucrose, fructose, or glucose. Inoculated samples were incubated anaerobically at 37 degrees C for 48 h. Samples were collected at 12-h intervals and examined for (i) specific growth rate, (ii) pH, and (iii) levels of fermentation end products (lactic and acetic acids) as measured by high-performance liquid chromatography (HPLC). Viability of the organisms during 28 days of refrigerated storage at 4 degrees C was also assessed at 7-day intervals. Growth promotion and acid production were greatest when Bf-1 and Bf-6 were grown in the presence of honey. For both Bf-1 and Bf-6, retention of viability was greatest up to 14 days of refrigerated storageat 4 degrees C when they were grown and stored in the presence of honey compared to other sweeteners.     

Room temperature electrodeposition of aluminum antimonide compound semiconductor

AlSb is a group III-V compound semiconductor material that is conventionally grown by high temperature processes such as Czochralski and Bridgman methods. Development of a method to synthesize AlSb at room temperature will be more economical to help modulate the electronic properties. In this investigation, a pulsed potential electrodeposition method using a room temperature molten salt system (aluminum trichloride, AlCl₃/1-methyl-3-ethylimidazolium chloride, EMIC) with an addition of SbCl₃ is discussed. The potential pulse parameters were established by carrying out cyclic voltammetry at different concentrations of SbCl₃ and with varying molar ratios of AlCl₃/EMIC. Stoichiometric AlSb deposits were obtained from an acidic AlCl₃/EMIC (1.5:1 molar ratio) melt containing 4 × 10⁻³ mol/l of SbCl₃ onto an ordered TiO₂ nanotubular template. The AlSb compound was predominantly amorphous in as-deposited condition and annealing at 350 °C for 2 h in argon transformed into crystalline phase. The AlSb deposit showed a high resistivity in the order of 10⁹ Ω-cm and a defect concentration of 10¹⁶ cm⁻³ which was attributed to presence of carbon. The deposits obtained from a basic melt (0.67:1 molar ratio of AlCl₃/EMIC) were enriched with antimony.     

Optomechanical scanning systems for microstereolithography (MSL): Analysis and experimental verification

Optomechanical scanning systems with focused laser spot are used in several applications including microstereolithography (MSL), scanning optical tweezers, and laser cutting. Systems used so far in the literature for scanning a focused laser spot on a substrate are: (a) galvanomirror preobjective scanning, (b) galvanomirror postobjective scanning and (c) ‘off-axis’ lens scanning system (originally proposed by coauthors). Major performance criteria due to end application, (say for example, to obtain high resolution microdevices in MSL) translates into the following criteria on optical scanning system: (i) uniform spot size and (ii) uniform intensity profile over the entire range of scan. This paper presents comparative optical analysis, both theoretical and experimental, of these systems based on the proposed performance criteria. Optical analysis of the optomechanical scanning systems is carried out by using geometric ray tracing method. Image evaluation in this case is done using diffraction wave optics. Simulations are carried out to determine spot characteristics at image plane when scan distances are changed by moving optics in the above mentioned optomechanical scanning systems. Simulation and experimental results clearly show that there is lesser distortion of spot characteristics (size and intensity profile) in case of proposed off-axis lens scanning system as compared to other systems over wider scan range. Hence this system is more promising to fabricate high resolution micro-components and in general for other similar applications as well.