Creep behavior of polyethylene melts

Creep behavior of branched polyethylene melts with various molecular weight distributions are examined experimentally. The order of the steady-state compliance is in accord with the prediction from the molecular weight distribution. The shear rate dependence of viscosity and steady-state compliance are analyzed according to Pao's theory.     

Radiation-induced oxidative degradation of poly(vinyl chloride)

Gas evolution and oxygen consumption in the γ-irradiation of PVC were studied. The gas evolution and the oxidative degradation are retarded by the presence of plasticizers and stabilizers. The G(HCI) and G(H₂) and 8 and 0.24 for the irradiation of pure PVC under vacuum and 0.02 and 0.14 for that of plasticized PVC, respectively. Gas evolution increases in the presence of oxygen, specially for the pure PVC. The G(–O₂) values for the pure and plasticized PVC are 30 and 12, respectively. The dependence of gas evolution and oxygen consumption on the oxygen pressure is more pronounced for the plasticized PVC than pure PVC because the oxygen diffusion is controlled.     

Brain potentials after clicking a mouse: a new psychophysiological approach to human-computer interaction

As a first step in developing a new psychophysiological technique to assess mental workload in human-computer interaction (HCI), we recorded event-related brain potentials for visual stimuli triggered by voluntary mouse clicks. Twelve university students clicked a mouse button at their own pace. Each click triggered 1 of 3 alphabetic letters assigned to frequent standard, rare target, and rare nontarget stimuli. Counting target stimuli was required. Both rare stimuli elicited a P3 (P300) wave, the amplitude of which was larger when the stimuli were triggered by mouse clicks than when the same stimuli were presented automatically without mouse clicks. Postmotor potentials associated with clicking were small in amplitude (<2 microV) and did not temporally overlap with the P3. The findings suggest that the P3 can be recorded for a computer's response to the user's intentional action and may be used as a measure of perceptual-central processing resources allocated to the HCI task. Actual or potential applications of this research include the evaluation of the user's attentional state during HCI byrecording brain potentials in the "mouse click" or action-perception paradigm.     

Fine silicon carbide fibers synthesized from polycarbosilane-polyvinylsilane polymer blend using electron beam curing

A fine SiC fiber is synthesized from a polymer blend of polycarbosilane (PCS) and polyvinylsilane (PVS) with electron beam curing under vacuum. The obtained SiC fiber from the PCS-PVS blend polymer has smaller average diameter of 8.5 m than that of 11.8 m from PCS, and shows higher average tensile strength of 3.2 GPa than that of 2.8 GPa from PCS after heat treatment at 1673 K in Ar gas atmosphere. However, the SiC fiber from the polymer blend decreases in tensile strength after heat treatment above 1773 K due to -SiC crystal growth near the fiber surface, because of a small amount of oxygen incorporated in the fiber.     

Solving shortest paths efficiently on nearly acyclic directed graphs

Shortest path problems can be solved very efficiently when a directed graph is nearly acyclic. Earlier results defined a graph decomposition, now called the 1-dominator set, which consists of a unique collection of acyclic structures with each single acyclic structure dominated by a single associated trigger vertex. In this framework, a specialised shortest path algorithm only spends delete-min operations on trigger vertices, thereby making the computation of shortest paths through non-trigger vertices easier. A previously presented algorithm computed the 1-dominator set in O(mn) worst-case time, which allowed it to be integrated as part of an O(mn+nrlogr) time all-pairs algorithm. Here m and n respectively denote the number of edges and vertices in the graph, while r denotes the number of trigger vertices. A new algorithm presented in this paper computes the 1-dominator set in just O(m) time. This can be integrated as part of the O(m+rlogr) time spent solving single-source, improving on the value of r obtained by the earlier tree-decomposition single-source algorithm. In addition, a new bidirectional form of 1-dominator set is presented, which further improves the value of r by defining acyclic structures in both directions over edges in the graph. The bidirectional 1-dominator set can similarly be computed in O(m) time and included as part of the O(m+rlogr) time spent computing single-source. This paper also presents a new all-pairs algorithm under the more general framework where r is defined as the size of any predetermined feedback vertex set of the graph, improving the previous all-pairs time complexity from O(mn+nr²) to O(mn+r³).     

Quantification of Dance Movement by Simultaneous Measurement of Body Motion and Biophysical Information

The purpose of this research is a quantitative analysis of movement patterns of dance,which cannot be analyzed with a motion capture system alone,using simultaneous measurement of body motion and biophysical information.In this research,two kinds of same leg movement are captured by simultaneous measurement;one is a leg movement with given strength,the other is a leg movement without strength on condition of basic experiment using optical motion capture and electromyography (EMG) equipment in order to quantitatively analyze characteristics of leg movement.Also,we measured the motion of the traditional Japanese dance using the constructed system.We can visualize leg movement of Japanese dance by displaying a 3D CG character animation with motion data and EMG data.In addition,we expect that our research will help dancers and researchers on dance through giving new information on dance movement which cannot be analyzed with only motion capture.     

Effect of Firing Temperature on the Thermal Stability of Low-Oxygen Silicon Carbide Fibers

Low-oxygen SiC fibers which were fabricated by curing with electron-beam irradiation and firing at 1273 and 1573 K (fiber-A and fiber-B) were exposed at 1673 to 1973 K. Significant differences in surface composition, crystallinity, specific resistivity, and tensile strength were found between fiber-A and fiber-B. On exposing the fibers to high temperatures, they both crystallized nearly completely into intermixed β-SiC and free carbon, and consequently the resistivity decreased markedly. Deep voids were formed at the surface of fiber-A as a result of rapid dehydrogenation at the earliest stage of high-temperature exposure. On the other hand, fiber-B, which decomposed mildly, had a dense pore-free structure. The fiber strength was proportional to the reciprocal square root of SiC crystal size. At the same crystal size, the strength of fiber-A was lower because of the surface flaws.     

PVC、EPR和CSM材料辐照后热氧化降解的反应动力学分析

采用气相色谱定量测量了聚氯乙烯(PVC)、乙丙橡胶(EPR)和氯磺化聚乙烯(CSM)等线缆绝缘材料经辐照后在不同温度下热老化过程中的O2消耗量.对实验数据进行了反应动力学分析,发现线缆绝缘材料的热氧化降解反应为一级反应.同时获得了不同温度下的反应常数,并与根据Arrhenius 方程计算的理论结果进行了比较.