Acceleration waves through a mixture of two non-linear elastic solids

Summary In this paper we study the propagation of acceleration waves through an anisotropic isothermal mixture of two non-linear elastic solids. First of all, we show that, under suitable hypotheses on the constitutive equations, there exist twelve real normal speeds of propagation; then by means of Nariboli method, we state the evolution law of the discontinuities along the rays associated with the wave front.Work performed under the auspices of C.N.R. (GNFM) and supported by M.P.I. of Italy.     

Experimental and numerical simulations of turbulent ventilation in aircraft cabins

Airflow in a generic airplane cabin has been investigated numerically by means of Reynolds averaged Navier–Stokes computations and experimentally by particle image velocimetry (PIV). High and low Reynolds number as well as two layer turbulence models were tested for their ability to describe turbulent velocity fields. Special attention was given to the flow of the incoming air jet along the luggage compartment. Comparison with PIV measurements reveals that for reliable prediction of isothermal cabin flow, low Reynolds number turbulence models have to be used.     

Prognostic significance of chromosome 17p deletions in childhood primitive neuroectodermal tumors (medulloblastomas) of the central nervous system

Until fairly recently, investigations into the control of cell production (proliferation) have been the mainstay of studies into the maintenance of mucosal homeostasis and general integrity. However, in addition to proliferation, it is now increasingly evident that programmed cell death, specifically that form of programmed cell death known as apoptosis, is an equally, if not more important, mechanism of regulating mucosal cell number. This review will concentrate on the significance of damage (radiation) induced and spontaneous apoptosis in the maintenance of intestinal epithelial stem cell number and integrity, and its probable link to the level of cancer incidence in the small intestine and colon.     

Channel allocation and medium access control for wireless sensor networks

Recent developments in sensor technology, as seen in Berkeley’s Mica2 Mote, Rockwell’s WINS nodes and the IEEE 802.15.4 Zigbee, have enabled support for single-transceiver, multi-channel communication. The task of channel assignment with minimum interference, also named as the 2-hop coloring problem, allows repetition of colors occurs only if the nodes are separated by more than 2 hops. Being NP complete, development of efficient heuristics for this coloring problem is an open research area and this paper proposes the Dynamic Channel Allocation (DCA) algorithm as a novel solution. Once channels are assigned, a Medium Access Control protocol must be devised so that channel selection, arbitration and scheduling occur with maximum energy savings and reduced message overhead, both critical considerations for sensor networks. The contribution of this paper is twofold: (1) development and analysis of the DCA algorithm that assigns optimally minimum channels in a distributed manner in order to make subsequent communication free from both primary and secondary interference and (2) proposing CMAC, a fully desynchronized multi-channel MAC protocol with minimum hardware requirements. CMAC takes into account the fundamental energy constraint in sensor nodes by placing them in a default sleep mode as far as possible, enables spatial channel re-use and ensures nearly collision free communication. Simulation results reveal that the DCA consumes significantly less energy while giving a legal distributed coloring. CMAC, our MAC protocol that leverages this coloring, has been thoroughly evaluated with various modes in SMAC, a recent protocol that achieves energy savings through coordinated sleeping. Results show that CMAC obtains nearly 200% reduction in energy consumption, significantly improved throughput, and end-to-end delay values that are 50–150% better than SMAC for our simulated topologies.     

Soybean Oil Fatty Acid Ester Estolides as Potential Plasticizers

Fatty acid ester estolides were synthesized from soybean oil and evaluated for plasticizer functionality in poly(vinyl chloride) (PVC). The plasticization ability of the fatty acid ester estolides depends upon the molecular features such as polarity, molecular weight, and branching. The structure of the fatty acid derivatives was modified at the ester head group with various alcohols and the estolide branch was created at the site of unsaturation. Soy fatty acid esters of methanol, iso-butanol, 2-ethylhexanol, and glycerol were prepared to vary the size and polarity at the ester head group. Estolides of these fatty acid esters were prepared using two synthetic routes. In the first route, the fatty acid ester was condensed with an aliphatic acid at the site of unsaturation in the presence of a strong mineral acid. In the second route, the fatty acid ester double bonds were converted to epoxy groups, which were ring opened and acetylated to form acetate estolides. The first synthetic route resulted in low-average estolide content per fatty acid chain while the second route resulted in a higher estolide content per fatty acid chain. The fatty acid ester estolides compounded with PVC showed good plasticizer properties as evidenced by the rheological properties and reduction in glass transition temperature. The fatty acid ester estolides with a higher estolide content had better plasticizer functionality, comparable to commercial controls.     

An enhanced copy-move forgery detection using machine learning based hybrid optimization model

Multimedia Tools and Applications - In recent years, one of the forgery detection methods is the Copy-Move Forgery Detection (CMFD), which is mostly used approach amongst all the forgery...     

On identification of Hammerstein and Wiener model with application to virtualised software system

This paper proposes a system identification method for estimating virtualised software system dynamics within the framework of a Hammerstein–Wiener model. Building on the authors’ previous work in identification and control of the software systems, the approach utilises frequency sampling filter structure to describe the linear dynamics and B-spline curve functions for the inverse static output nonlinearity. Furthermore, the issue on parameter selection for B-spline model approximation of scatter data is addressed by using a data clustering method. An experimental test-bed of virtualised software system is established to generate real observational data which are used to confirm the performance of the proposed approach. The identification results have shown that the model efficacy is increased with the proposed approach because the dimension of the nonlinear model can be significantly reduced while maintaining the desired accuracy.     

LAMINAR FILM BOILING ON A VERTICAL SURFACE WITH THERMAL LEAKAGE AT ITS ENDS

The analysis presented is for laminar film boiling on a vertical surface treating the test section as a fin with the heat leakage from its ends. The formulation of the problem is accomplished as a conjugate between the thermal conduction in the test section and the phenomenon of film boiling on its lateral face. This approach revealed that the film boiling heat transfer coefficients, both local and average values, are profoundly influenced by the fin parameter. An explicit form of the equation is provided from the computer results to evaluate the film boiling heat transfer coefficient.     

Proposed design methods for lateral torsional buckling of unrestrained steel beams in fire

The behaviour of unrestrained steel I-beams has been studied by means of numerical analysis and published experimental results. The numerical model was developed using a commercial finite element program, MSC.MARC Mentat. A series of different UB and UC sections and different spans, subjected to both uniform moment and midspan point loads, are considered. The numerical predictions of the buckling moments are then compared with published experimental results. Consequently, a new approach is proposed to provide more accurate and safe predictions of the fire resistance of unrestrained beams, as well as to overcome certain weaknesses in the EC3:1.2 [European committee for standardization (CEN). Eurocode 3: Design of steel structures, Part 1.2: General rules — structural fire design, EN 1993-1-2. Brussels (Belgium); 2005] design formula. In addition, to provide a quick and simple design approach for engineers, a straightforward and rational method known as the Rankine method is introduced to predict the LTB failure load of steel beams in fire. It is shown that the Rankine approach generally provides a good lower bound value for numerical predictions.     

火灾中无约束钢梁的扭转弯曲的设计方法

采用数字分析和相关试验结果研究了无约束钢I截面梁的行为,采用有限元程序拓展了数学模型。在相同弯矩和中跨集中荷载的情况下,对一系列不同的UB和UC截面以及不同跨度,进行了研究。比较了预估的弯矩值与相关试验结果。在此基础上,对无约束梁提出了一种新的更精确和安全防火预报的方法,该方法克服了欧洲规范（EC3：1．2）设计公式中的一些弱点。另外,给设计者提供了一个便捷和简单的设计方法,即该方法易懂又合理,称为兰金方法。可用于预估钢梁在火中的LTB破坏荷载。兰金方法为数值预估提供了一个适宜的下界值。