An unsupervised approach to generating generic summaries of documents

We present an optimization-based unsupervised approach to automatic document summarization. In the proposed approach, text summarization is modeled as a Boolean programming problem. This model generally attempts to optimize three properties, namely, (1) relevance: summary should contain informative textual units that are relevant to the user; (2) redundancy: summaries should not contain multiple textual units that convey the same information; and (3) length: summary is bounded in length. The approach proposed in this paper is applicable to both tasks: single- and multi-document summarization. In both tasks, documents are split into sentences in preprocessing. We select some salient sentences from document(s) to generate a summary. Finally, the summary is generated by threading all the selected sentences in the order that they appear in the original document(s). We implemented our model on multi-document summarization task. When comparing our methods to several existing summarization methods on an open DUC2005 and DUC2007 data sets, we found that our method improves the summarization results significantly. This is because, first, when extracting summary sentences, this method not only focuses on the relevance scores of sentences to the whole sentence collection, but also the topic representative of sentences. Second, when generating a summary, this method also deals with the problem of repetition of information. The methods were evaluated using ROUGE-1, ROUGE-2 and ROUGE-SU4 metrics. In this paper, we also demonstrate that the summarization result depends on the similarity measure. Results of the experiment showed that combination of symmetric and asymmetric similarity measures yields better result than their use separately.     

Voltage reference architectures for low-supply-voltage low-power applications

This paper presents a voltage reference generator architecture and two different realizations of it that have been fabricated within a standard 0.18 μm CMOS technology. The architecture takes the advantage of utilizing a sampled-data amplifier (SDA) to optimize the power consumption. The circuits achieve output voltages on the order of 190 mV with temperature coefficients of 43 ppm/°C and 52.5 ppm/°C over the temperature range of 0 to 120°C without any trimming with a 0.8 V single supply. The power consumptions of the circuits are less then 500 nW while occupying an area of 0.2 mm² and 0.08 mm², respectively.     

The Radical Versus Non-radical Reactive Intermediates in the Iron(III) Porphyrin Catalyzed Oxidation Reactions by Hydroperoxides, Hydrogen Peroxide and Iodosylarene

In the catalytic reaction of an iron(III) porphyrin with t-BuOOH, CumOOH, H₂O₂ and C₆F₅IO, cyclohexene was used as a probe substrate. The selective hydroxylation of cyclohexene by hydroperoxides proceeds through radical path and this has been utilized for successful dioxygen activation/autooxidation. For other oxidants epoxide was the major product and the reactions proceed through non-radical path.     

Aging response of the young’s modulus and mechanical properties of Ti-29Nb-13Ta-4.6Zr for biomedical applications

Alloys for implant devices require improved strength but a reduced Young’s modulus, in order to become mechanically more compatible with adjacent bone tissues. In this study, a new metastable β-type titanium alloy, Ti-29Nb-13Ta-4.6Zr (wt pct), was subjected to aging treatment to produce different microstructures, and the resulting mechanical properties, including the Young’s modulus, were measured. The Young’s modulus of this alloy is found to be sensitive to microstructures generated by various heat treatments. For microstructures varying from (α + β) to (α + β + ω) and (β + ω), the Young’s modulus increases with an accompanying increase in tensile strength and hardness, but decreases in ductility. The (β + ω) microstructure has a low strength, high modulus, and poor ductility and cannot be used for biomedical applications. For an (α + β) microstructure, the volume fraction of the phases is shown to be the main factor that determines the mechanical properties.     

Theoretical investigations on the spin Hamiltonian parameters for Er3+ ion in LiYF4

The spin Hamiltonian parameters g_∥, g_⊥, A_∥ and A_⊥ for Er³⁺ ion in LiYF₄ are investigated by using the perturbation formulas of these parameters for a 4f¹¹ ion in tetragonal symmetry. In these formulas, the contributions to the spin Hamiltonian parameters from the second-order perturbation terms and the admixtures of different states are considered. The relevant crystal field parameters are calculated from the superposition model and the local structural parameters of the Y³⁺ site occupied by impurity Er³⁺. The theoretical optical spectra within ⁴I_15/2 and ⁴I_13/2 states and the spin Hamiltonian parameters obtained in this work are consistent with the observed values.     

Influence of Ti Powder Characteristics on Combustion Synthesis of Porous NiTi Alloy

Porous NiTi shape memory alloy (SMA) is a novel biomedical material used for human hard tissue implant .The influence of elemental titanium powder characteristics such as powder morphology, particle size and specific surface area( SSA) on the minimal ignition temperature ,combustion temperature and final product of porous Ni-Ti SMA fabricated by combustion synthesis method was investigated in this paper by scanning electron microscopy (SEM) and laser diffraction.The preliminary data indicated that the titanium powder characteristics had a strong effect on combustion synthesis of porous NiTi SMA.     

Models for the determination of kinetic phase diagrams and kinetic phase separation domains

Several theoretical models for the determination of kinetic phase diagrams for solid solution growth from the liquid phase are presented and compared to each other. These models include a Monte Carlo simulation model, used as a reference model, a previously defined analytical model, based on linear non-equilibrium thermodynamics, and a new model, rooted in the kinetics at kink sites.All models have in common that the composition of the growing solid phase tends to the liquid phase composition for increasing undercooling, enhancing mixing even for systems with a strong tendency to phase separation. However, depending on the system parameters considerable quantitative differences can occur between the results from the model based on non-equilibrium thermodynamics and the MC model. Instead, the new model follows very well the trends of the MC simulations, both for well-mixing systems and for phase separating systems.For phase separating systems the analytical models predict kinetic phase separation domains, zones in the kinetic phase diagram yielding steady state growth of more than one solid phase with different compositions. According to MC simulations such domains in phase space correspond to domain formation in real space. Also in this case the new model is consistent with the MC results.