Simply supported Michell trusses generated by a lateral point load

The paper deals with the optimum design problem posed by George Rozvany: find the lightest fully stressed truss transmitting a given concentrated force to two supports forming a line parallel to the force. One of the supports is a hinge while the second one is a roller. The feasible domain is a square domain over the line linking the supports. The problem thus formulated belongs to the class of the three force problem, till now unsolved in general. In the problem stated here two of the three forces are mutually orthogonal. The family of solutions to this problem is parameterized by the coordinates of the point of the force application, hence is a two-parameter family. This seemingly simple problem generates a vast family of extremely interesting solutions, some of them being known, some being only partly resolved, while others turn out to be surprising and not resolved till now. The present paper delivers exact solutions to the optimum designs corresponding to the force position being a sufficiently big distance to the line linking the supports. The kinematic and static approaches are used, both leading to the same exact results. Other solutions are constructed numerically by the adaptive ground structure method.     

A 99 line code for discretized Michell truss optimization written in Mathematica

The main purpose of the paper is to provide an easy-to-use code for topological optimization of the least weight trusses, written in the Mathematica programming language. The main idea of the presented approach consists in using a fixed ground structure and the linear programming formulation of the optimization problem. The solver is based on the fast interior point method. The strong effort is done to create the effective generator of the computational model utilizing the high regularity of the ground structure and the high sparsity of the geometric matrix. The efficiency and reliability of the algorithm is confirmed in several numerical tests. Due to a linear programming formulation of the optimization problem the method presented in the paper assures finding the global optimum, hence it may be considered as the useful tool for verification of results obtained in other ways. The appended complete Mathematica code of the program developed will be supplied by the Publisher on SpringerLink.     

In vitro release of α-tocopherol from emulsion-loaded β-lactoglobulin gels

Cold-set oil-loaded protein gels based on an emulsifying step followed by Ca²⁺-induced gelation of pre-denatured β-lactoglobulin (β-LG) have been recently developed. In vitro release and stability of a fat-soluble compound (α-tocopherol) therein were investigated in this work. Release of α-tocopherol was found to be controlled mainly by matrix erosion due to protein degradation. Compound release and matrix erosion were almost complete after incubation under gastric or intestinal conditions for 6.5 h. However, both processes were basically inhibited upon changing the dissolution medium from the gastric to the intestinal type, possibly due to β-LG partial hydrolysis products with greater emulsifying capacity anchoring to the surface of gel oil droplets. The stability of released α-tocopherol was apparently improved by binding to protein and/or hydrolysis products thereof.     

Factors associated with automobile accidents and survival

This paper develops an econometric model for vehicles' inherent mortality rate and estimates the probability of accidents and survival in the United States. Logistic regression model is used to estimate probability of survival, and censored regression model is used to estimate probability of accidents. The estimation results indicated that the probability of accident and survival are influenced by the physical characteristics of the vehicles involved in the accident, and by the characteristics of the driver and the occupants. Using restrain system and riding in heavy vehicle increased the survival rate. Middle-aged drivers are less susceptible to involve in an accident, and surprisingly, female drivers are more likely to have an accident than male drivers. Riding in powerful vehicles (high horsepower) and driving late night increase the probability of accident. Overall, the driving behavior and characteristics of vehicle does matter and affects the probabilities of having a fatal accident for different types of vehicles.     

Effect of temperature and PH value on the stability of bioactive compounds and antioxidative activity of juice from colour-fleshed potatoes

The colour-fleshed potatoes represent a good raw material for the extraction of juices with a high content of biologically active compounds and a high antioxidant activity. The blue-fleshed potatoes turned out to be a rich source of total polyphenols, as they had approximately 3.5 times higher content of identified anthocyanidins. Regardless of anthocyanin composition, all juices made of colour-fleshed potatoes were highly stable. Both, high temperature, exposure time to these temperatures, and medium pH had no significant effect on changes in total polyphenols content of potato juices. The juices examined, especially these made of blue-fleshed potatoes, demonstrated a higher ABTS+ stability during their heating than during pH changes. In addition, a higher antioxidant activity of juices was determined at neutral and alkaline than at acidic pH value of the medium.     

Fast-path I/O architecture for high performance streaming server

In a disk-network scenario where expensive data transfers are the norm, such as in multimedia streaming applications, for example, a fast-path I/O architecture is generally considered to be “good practice.” Here, I/O performance can be improved through minimizing the number of in-memory data movements and context switches. In this paper, we report the results of the design and implementation of a high-performance streaming server using cheap hardware units assembled directly on a test card (i.e., NS card). The hardware part of our architecture is open to further reuse, extension, and integration with other applications even in the case of inexpensive and/or faster hardware. From the viewpoint of software-aided I/O, we offer Stream Disk Array (SDA) for scatter/gather-style block I/O, EXT3NS multimedia file system for large-scale file I/O, and interoperable streaming server for stream I/O.     

Droplet-Based Microreactions With Oil Encapsulation

This paper reports a microreaction technology for biochemical assay using nanoliter droplets encapsulated inside oil droplets. Microreaction chambers are constructed on a glass substrate by accumulating oil droplets that are dispensed by a directional droplet ejector. Droplets of different aqueous reagents are then directionally ejected (by other directional droplet ejector adjacent to the oil droplet ejector) into the oil microchambers for parallel and combinatory analysis. Because the reagents are encapsulated in oil, the evaporation rate is reduced by several orders of magnitude, and only small amounts of reagents are required for each assay. The microchamber size and the reagent amount are digitally controlled by the number of ejected oil and reagent droplets, respectively. The ejectors for oil and reagents have been integrated on a single chip so that each assay is performed efficiently without any mechanical movement and alignment. We have carried out both physical and chemical microreactions with this method and observed a negligible difference in response from conventional macroreactions.     

Single- and Triaxis Piezoelectric-Bimorph Accelerometers

This paper describes the novel single- and triaxis piezoelectric-bimorph accelerometers that are built on parylene beams with ZnO films. The unamplified sensitivity and the minimum detectable signal of the fabricated single-axis accelerometer are measured to be 7.0 mV/g and 0.01 g, respectively, over a frequency range from 60 Hz to subhertz. The linearity of the sensitivity as a function of acceleration is measured to be 0.9% in the full scale. A highly symmetric quad-beam bimorph structure with a single proof mass is used for triaxis acceleration sensing and is demonstrated to produce high sensitivity, low cross-axial sensitivity, and good linearity, all in a compact size. The unamplified sensitivities of the X-, Y-, and Z-axis electrodes (of the triaxis accelerometer) in response to the accelerations in X-, Y-, and Z-axes are 0.93, 1.13, and 0.88 mV/g, respectively. The worst-case minimum detectable signal of the triaxis accelerometer is measured to be 0.04 g over a bandwidth ranging from subhertz to 100 Hz. The cross-axial sensitivity among the X-, Y-, and Z-axis electrodes is less than 15% in the triaxis accelerometer. The theoretical analyses of the charge sensitivities and resonant frequencies along with the effects of residual stress on the charge sensitivities are presented for both the single- and triaxis accelerometers.     

Optimal design of a class of symmetric plane frameworks of least weight

The aim of the paper is to place the recent results on the Michell-like problem of transmitting two vertical forces to two fixed hinge supports in the context of C. Maxwell’s result and to provide answers to the remarks by Vázquez Espií and Cervera Bravo (Struct Multidisc Optim, 2011) published in their Discussion Paper: On the solution of the three forces problem and its application in optimal designing of a class of symmetric plane frameworks of least weight. Discussion on the Michell class concept.     

Piezoelectric bimorph microphone built on micromachined parylene diaphragm

This paper describes a novel bimorph piezoelectric microphone built on a micromachined parylene diaphragm with two ZnO films of opposite c-axis orientations. Both the sensitivity and signal-to-noise ratio (SNR) of the bimorph parylene-diaphragm microphone have been demonstrated to be much higher than those of a conventional unimorph silicon-nitride-diaphragm microphone.