Statistical distribution of the envelope of an amplitude-modulated laser signal after passage through a turbulent atmosphere

The influence of turbulence on the statistical distribution of the envelope of a modulated laser signal is experimentally investigated. From the experiments, it has been found that the distribution is considerably dependent on the distance.     

A Decision-Making Model for Applications of Queueing Theory

The purpose of this article is to present and illustrate a general framework for decision-making problems associated with queueing systems. The proposed feedback model is a generalization of the type of open-loop cost model usually encountered in the queueing literature. The model is discussed in the context of simple service systems for which queueing theory can provide the required queueing statistics. The use of the model is first illustrated by an M|M| 1 example, for which solutions are obtainable in closed-form and sensitivity to parameters is easily explored. In general, extensions from the basic example will require solution of nonlinear programming problems. This is illustrated by using the constant service-time variation of the example to obtain some comparative results.     

The chain transfer to polymer in vinyl chloride bulk polymerization

Summary Self grafting of PVC has been studied by introducing a 36-chlorine labelled low molecular PVC fraction in the polymerization mixture of vinyl chloride. The fractionation of the polymer obtained follows the same pattern as a synthetic mixture of the polymer with the same fraction. It is concluded that, under those working conditions, chain transfer to the polymer with grafting has not taken place, at least in a considerable extent.     

Parameterized complexity of three edge contraction problems with degree constraints

For any graph class \(\mathcal{H}\) , the \(\mathcal{H}\) -Contraction problem takes as input a graph \(G\) and an integer \(k\) , and asks whether there exists a graph \(H\in \mathcal{H}\) such that \(G\) can be modified into \(H\) using at most \(k\) edge contractions. We study the parameterized complexity of \(\mathcal{H}\) -Contraction for three different classes \(\mathcal{H}\) : the class \(\mathcal{H}_{\le d}\) of graphs with maximum degree at most  \(d\) , the class \(\mathcal{H}_{=d}\) of \(d\) -regular graphs, and the class of \(d\) -degenerate graphs. We completely classify the parameterized complexity of all three problems with respect to the parameters \(k\) , \(d\) , and \(d+k\) . Moreover, we show that \(\mathcal{H}\) -Contraction admits an \(O(k)\) vertex kernel on connected graphs when \(\mathcal{H}\in \{\mathcal{H}_{\le 2},\mathcal{H}_{=2}\}\) , while the problem is \(\mathsf{W}[2]\) -hard when \(\mathcal{H}\) is the class of \(2\) -degenerate graphs and hence is expected not to admit a kernel at all. In particular, our results imply that \(\mathcal{H}\) -Contraction admits a linear vertex kernel when \(\mathcal{H}\) is the class of cycles.     

Variation with chain length in acute toxicity of alkylhydroxamic acids to salmon (Salmo salar) fry

The acute toxicity of saturatedn-alkylhydroxamic acids to salmon (Salmo salar) fry was determined. Within the seriesn-C₆H₁₃CONHOH ton-C₁₀H₂₁CONHOH, acute toxicity (indicated by death) increased with chain length. Shorter and longer chain compounds were not toxic under similar conditions. Factors governing the variation in toxicity with chain length and possible mechanisms of action are discussed. Presented in part at the AOCS Meeting, Atlantic City, October 1971.     

Mechanical properties of directionally solidified lead-antimony alloys

The Pb-17wt％ Sb alloy was directionally solidified under two solidification conditions:with different temperature gradients (G=0.93-3.67 K/mm)at a constant growth rate(V=17.50 μm/s)and with different growth rates(V=8.3-497 μm/s)at a constant temperature gradient(G=3.67 K/mm)in a Bridgman furnace.Microstructure parameters,such as primary dendrite arm spacing(λ1),secondary dendrite arm spacing(λ2),and dendrite tip radius(R),were measured.The microhardness(Hv)and ultimate tensile strength(σ)of the directional solidification samples were also measured.The influences of solidification and microstructure parameters on Hv and σrwere investigated.The results obtained in this work were compared with similar experimental researches in literatures.It is shown that the Hv and σrvalues increase with the increase of G and V,but decrease with the increase of λ1,λ2,and R.     

High Current Density Electrical Breakdown of TiS3 Nanoribbon‐Based Field‐Effect Transistors

The high field transport characteristics of nanostructured transistors based on layered materials are not only important from a device physics perspective but also for possible applications in next generation electronics. With the growing promise of layered materials as replacements to conventional silicon technology, the high current density properties of the layered material titanium trisulfide (TiS₃) are studied here. The high breakdown current densities of up to 1.7 × 10⁶ A cm^?2 are observed in TiS₃ nanoribbon‐based field‐effect transistors, which are among the highest found in semiconducting nanomaterials. Investigating the mechanisms responsible for current breakdown, a thermogravimetric analysis of bulk TiS₃ is performed and the results with density functional theory and kinetic Monte Carlo calculations are compared. In conclusion, the oxidation of TiS₃ and subsequent desorption of sulfur atoms play an important role in the electrical breakdown of the material in ambient conditions. The results show that TiS₃ is an attractive material for high power applications and lend insight into the thermal and defect activated mechanisms responsible for electrical breakdown in nanostructured devices.     

The Case for Polymorphic Registers in Dataflow Computing

Heterogeneous systems are becoming increasingly popular, delivering high performance through hardware specialization. However, sequential data accesses may have a negative impact on performance. Data parallel solutions such as Polymorphic Register Files (PRFs) can potentially accelerate applications by facilitating high-speed, parallel access to performance-critical data. This article shows how PRFs can be integrated into dataflow computational platforms. Our semi-automatic, compiler-based methodology generates customized PRFs and modifies the computational kernels to efficiently exploit them. We use a separable 2D convolution case study to evaluate the impact of memory latency and bandwidth on performance compared to a state-of-the-art NVIDIA Tesla C2050 GPU. We improve the throughput up to 56.17X and show that the PRF-augmented system outperforms the GPU for \(9\times 9\) or larger mask sizes, even in bandwidth-constrained systems.     

A fuzzy overlay model for mapping adverse event risk in an active war theatre

This study discusses a series of fuzzy overlay analysis performed within a Geographic Information System (GIS) on recent adverse events throughout the war in Afghanistan. Three types of input variables are considered in terms of number of people killed, wounded and hijacked over the period 2004–2010 in order to identify the risk level in Afghanistan using fuzzy GIS approach. To conclude, most risky areas are accumulated in the eastern region of the country and major population centres. The proposed approach could enable military decision-makers to obtain a better understanding of the socio-spatial dynamic of incidents in Middle East.