Static scheduling for barrier MIMD architectures

In a SIMD or VLIW machine, conceptual synchronizations are accomplished by using a static code schedule that does not require run-time synchronization. The lack of run-time synchronization overhead makes these machines very effective for fine-grain parallelism, but they cannot execute parallel code structures as general as those executed by MIMD architectures, and this limits their utility.In this paper we present a timing analysis that allows a compiler for a MIMD machine to eliminate a large fraction of the run-time synchronization by making efficient use of static code scheduling. Although these techniques can be adapted to be applied to most MIMD machines, this paper centers on the analysis and scheduling for barrier MIMD machines. Barrier MIMDs are asynchronous multiple instruction stream/multiple data stream architectures capable of parallel execution of variable execution-time instructions and arbitrary control flow (e.g., while loops and calls). However, they also incorporate a special hardware barrier synchronization mechanism that facilitates static scheduling by providing a mechanism which the compiler can use to enforce precise timing constraints. In other words, the compiler tracks relative timing between processors and uses static code scheduling until the timing imprecision becomes too large, at which point the compiler simply inserts a barrier to reduce that timing imprecision to zero (or a small constant).This paper describes new scheduling and barrier placement algorithms for barrier MIMDs that are based loosely on the list scheduling approach employed for VLIWs [Ellis 1985]. In addition, the experimental results from scheduling thousands of synthetic benchmark programs for a parameterized barrier MIMD machine are presented.     

Prediction of Tool Wear in the Turning Process Using the Spectral Center of Gravity

The recent increase in machining productivity is closely related to longer tool life and good surface quality. In the present study, an experimental technique is proposed to evaluate the performance of a cemented carbide inset during the machining of AISI D3 steel. The aim of this technique is to find a relationship between the vibratory state of the cutting tool and the corresponding wear during machining in order to detect the beginning of the transition period to excessive wear. A spectral indicator named spectral center of gravity, SCG, is proposed to highlight the three phases of tool wear using the spectra of the accelerations measured. Very promising results are obtained which can be used to underpin an industrial monitoring system capable of detecting the onset of transition to excessive wear and alerting the user of the end of the tool’s life. The purpose of this study is to review the vibration analysis techniques and to explore their contributions, advantages and drawbacks in monitoring of tool wear.     

Optimization of Nebhana Reservoir Water Allocation by Stochastic Dynamic Programming

This study is devoted to the identification of an optimal rule that would permit to improve the water resources management of dam in arid condition. The Nebhana dam is considered in this study as a representative of a set dams situated in such condition. The water storage is used for irrigation purpose. The identification of an optimal rule is based on two opposite objectives: the satisfaction of the irrigation water demand and the safeguard of a minimal water storage in the dam. By considering different weights for these objectives, the stochastic dynamic programming technique was lead to various optimal rules for the water resources management of the Nebhana dam. This technique takes into account the variability of the volume of water inflow to the dam on the basis of their occurrence probability; the water losses by means of forecasting models and the water resources goals using weight coefficients. The identified optimal rule would permit to estimate the necessary water release volume for irrigation by considering the water storage and the decision period.     

Preparation,Infra-red,MAS-NMR and Structural Characterization of a New Copper Based Inorganic–Organic Hybrid Compound: [C<Subscript>5</Subscript>H<Subscript>6</Subscript>N<Subscript>2</Subscript>Cl]<Subscript>2</Subscript>CuCl<Subscript>4</Subscript>

The ionic salt [2(C₅H₆N₂Cl)⁺], [CuCl₄]^2? complex of copper(II) has been synthesized and characterized. The X-ray diffraction analysis with a single crystal of this compound showed that the title compound (4-amino-2-chloropyridinium)₂CuCl₄ [(CAP)₂CuCl₄], crystallized at room temperature in the monoclinic system, space group C_2/c (N°.15) and the following : a = 16.0064 (2) Å; b = 7.7964 (10) Å; c = 14.7240 (2) Å; β = 102.497 (10)°; V = 1793.91 (4) ų and Z = 4. The structure was solved by using 1,589 independent reflections down to R value of 0.021. The unit cell is made up of tetrachlorocuprate(II) anions and 4-amino-2-chloropyridinium cations linked together by an extensive hydrogen bond network of types N–H···Cl (N: pyridinium) and N–H···Cl (N: amine), and cation-lone pair of nitrogen element interactions. Solid state NMR spectra showed one and five isotropic resonances, ⁶³Cu and ¹³C, respectively, confirming the solid state structure determined by X-ray diffraction. Impedance spectroscopy study, reported for single crystal, revealed that the conduction in the material was due to a hopping process. This work aims to reveal the thermal properties of a new copper(II) based organic–inorganic hybrid and the conductivity properties that these compounds exhibit.     

Microstructure development,hardness, toughness and creep behaviour of pressureless sintered alumina/SiC micro–nanocomposites obtained by slip-casting

Al₂O₃–SiC micro–nanocomposites are much more resistant materials than monolithic alumina regarding some mechanical properties. In order to study the possibility of obtaining creep resistant alumina/SiC micro–nanocomposites using inexpensive forming methods, alumina 1 and 5 vol% SiC materials were produced by slip-casting and pressureless sintering. Well-densified alumina–SiC pressureless sintered materials were obtained at 1700 °C for 2 h and attained 97–99% of the theoretical density. The microstructure, hardness and toughness were examined and 4-point flexure creep tests were performed at 1200 °C and 100 MPa in air. Compared with pure alumina materials, the creep resistance, toughness and hardness were enhanced drastically in materials containing 5 vol% of SiC.     

Development of Cys38 knock-out and humanized version of NbAahII10 nanobody with improved neutralization of AahII scorpion toxin

During scorpion envenoming, highly toxic small polypeptides of the venom diffuse rapidly within the victim, causing serious medical problems. Nanobodies (Nbs), the recombinant single-domain antigen-binding fragments of camel-specific heavy-chain only antibodies, offer special advantages in therapy over classic antibody fragments due to their robustness and smaller size, matching the size of the scorpion toxins. Recently, a potent AahII scorpion toxin-neutralizing Nb was identified. However, this NbAahII10 contains a single Cys in its first antigen-binding loop, leading to Nb dimerization upon prolonged storage. In this work, we first investigate the efficacy of NbAahII10 variants in which this Cys was substituted by Ala, Ser or Thr. Second, the NbAahII10 Cys/Ser mutant displaying the best functional properties is subsequently humanized. It is demonstrated that the maximally humanized version of NbAahII10 Cys/Ser maintains its high affinity for the antigen without conceding much on expression yield and stability. More importantly, its neutralizing capacity is preserved as all mice survive injections of seven LD(50) and 50% of mice survived nine LD(50) of the scorpion toxin. Thus, this humanized Nb is the best candidate to develop a therapy in human against the most toxic venom compound of one of the most dangerous scorpions.