Densities and molal volumes ofn-alkylamines from 15 to 80°C

Densities of sevenn-alkylamines from 1-butylamine to 1-decylamine were determined from 15 to 80°C. The density was found to be a linear function of the temperature within this temperature range. At constant temperature, the molal volume was a linear function of the number of methylene units in the chain for the homologous series. A simple equation with four constants correlating the molal volume with the number of methylene units and temperature of then-alkylamines was formulated. Excellent agreement between the calculated, the measured and the literature values were obtained. Accurate molal volumes, and hence the densities of anyn-alkylamines, other than methylamine, within the temperature range can be calculated from the equation.     

SnSb@carbon nanocable anchored on graphene sheets for sodium ion batteries

The development of materials with unique nanostructures is an effective strategy for the improvement of sodium storage in sodium ion batteries to achieve stable cycling performance and good rate capability. In this work, SnSbcore/carbon-shell nanocables directly anchored on graphene sheets (GS) were synthesized by the hydrothermal technique and chemical vapor deposition. The simultaneous carbon coating and the encapsulation of SnSb alloy is effective for alleviating the volume-change problem in sodium ion batteries. After optimizing the electrolyte for SnSb in the sodium ion batteries, the optimized coaxial SnSb/carbon nanocable/GS (SnSb/CNT@GS) nanostructure demonstrated stable cycling capability and rate performance in 1 M NaClO₄ with propylene carbonate (PC) + 5% fluoroethylene carbonate (FEC). The SnSb/CNT@GS electrode can retain a capacity of 360 mAh/g for up to 100 cycles, which is 71% of the theoretical capacity. This is higher than in the other three electrolytes tested (1 M NaClO₄ in PC, 1 M NaClO₄ in PC/FEC (1:1 v/v) and 1 M NaPF₆ + PC), and higher than that of the sample without the addition of graphene. The good electrochemical performance can be attributed to the efficient buffering provided by the outer carbon nanocable layer and the graphene inhibiting the agglomeration of SnSb particles, as well as its high conductivity.      

Enhanced friction model for high-speed right-angle gear dynamics

The modeling of elastohydrodynamic lubrication friction and the analysis of its dynamic effect on right-angle gears, such as hypoid and spiral bevel types are performed in the present study. Unlike the classically applied empirical constant coefficient of friction at the contacting tooth surfaces, the enhanced physics-based gear mesh friction model is both spatial and time-varying. The underlying formulation assumes mixed elastohydrodynamic lubrication (EHL) condition in which the division and load distribution between the full film and asperity contact zones are determined by the film thickness ratio and load sharing coefficient. In the proposed time-varying friction model, the calculation of friction coefficient is performed at each contact grid inside the instantaneous contact area that is being subjected to mineral oil lubrication. The effective friction coefficient and directional parameters synthesized from the net frictional and normal contact forces are then incorporated into a nonlinear time-varying right-angle gear dynamic model. Using this model, the effect of friction on the gear dynamic response due to the transmission error and mesh excitations is analyzed. Also, parametric studies are performed by varying torque, surface roughness and lubrication properties to understand the salient role of tooth sliding friction in gear dynamics. The simulation results are included. But experimental verification is needed.     

Hysteretic behaviour of square tubular T-joints with chord reinforcement under axial cyclic loading

The stiffness of hollow section tubular joints is weak in the chord radial direction, and thus failure frequently occurs at the weld toe in the form of brittle fracture caused by crack propagation due to cyclic loading. To avoid such brittle failure, the chord at the intersection can be reinforced by increasing the chord thickness. With the chord reinforced, the failure position can be transferred to the chord intersection, and hence the cracking along the weld toe is prevented. To verify the efficiency of the proposed reinforcing method, both experimental test and finite element analysis are carried out on reinforced and un-reinforced square tubular T-joints subjected to quasi-static cyclic loads. The hysteretic curves, ductility ratio, energy dissipation and failure mode of the two full-scale specimens are studied experimentally, and it is found that the hysteretic curves of both specimens are plump, which show the T-joints can absorb much energy when they are subjected to seismic action. However, the enclosed area of the hysteretic curves of the reinforced T-joint is larger than that of the un-reinforced specimen because the chord reinforcement can prevent the fracture failure as well as improving the bearing capacity. The failure performance of the reinforced and un-reinforced specimens also show that a T-joint with chord reinforcement is more advantageous in resisting seismic action. Finally, the effect of the reinforced chord length and thickness on the hysteretic behaviour of square tubular T-joints is also investigated from a parametric study.     

Decomposition of singular large sparse matrix by adding dummy links and dummy degrees

Abstract

This paper proposes a simple scheme to decompose an n×n nonpositive definite matrix, A, associated with simultaneous equations, A X = B, into a triple‐factors (lower triangular, diagonal, and upper triangular matrices), i.e., Å = L D U, without interchanging rows or columns of A, but with A expanded with new rows and new columns to an m×m matrix Å. Whenever a near‐zero diagonal element, say ā_ii , is encountered and used as a pivoting element, an appropriate positive real number, say p, is added to this diagonal element, and a new term —px_k is also added to the i‐th equation, where x_k is a new variable called “dummy variable'’. If we also add a new equation —px_i + px_k = 0 to enforce the new added variable x_k equal to x_i then the modified i‐th equation has the same effect as the original equation. Therefore, the original solution X can be found directly from the expanded solution of the modified expanded equation. The method is very useful in solving the following problems: (1) nonlinear problems near the limit state, (2) postbuckling analysis, (3) system equations with constraint conditions, and (4) getting eigenvectors from eigenvalues.     

尼龙输送带热硫化粘接典型问题分析

介绍了皮带硫化粘接的工艺特点,指出了传统的硫化粘接工艺的不足之处,分析了皮带粘结中存在的问题,采用了相应的技术措施,从而有效提高了皮带接口的安全性,以提高其使用寿命.     

A mechanism of charge-carrier photogeneration in polyamidine supramolecular structures

The photophysical properties and mechanism of charge-carrier photogeneration in supramolecular polyamidine structures (which form, as was shown previously, a promising class of materials for photosensitive and electroluminescent devices) are studied. Based on the analysis of the spectral, field, temperature, and concentration behavior of changes in the photosensitive and luminescence properties, it is shown that the carrier photogeneration in the systems under investigation is described by the Pool-Frenkel model, which takes into account strong interactions and collective effects in the supramolecular system arising due to the formation of a regular network of hydrogen bonds between functional groups of a polymer.     

Treatment of intrahepatic cancers with radiation doses based on a normal tissue complication probability model

PURPOSE: To attempt to safely escalate the dose of radiation for patients with intrahepatic cancer, we designed a protocol in which each patient received the maximum possible dose while being subjected to a 10% risk of radiation-induced liver disease (RILD, or radiation hepatitis) based on a normal tissue complication probability (NTCP) model. We had two hypotheses: H1; with this approach, we could safely deliver higher doses of radiation than we would have prescribed based on our previous protocol, and H2; the model would predict the observed complication probability (10%). PATIENTS AND METHODS: Patients with either primary hepatobiliary cancer or colorectal cancer metastatic to the liver and normal liver function were eligible. We used an NTCP model with parameters calculated from our previous patient data to prescribe a dose that subjected each patient to a 10% complication risk within the model. Treatment was delivered with concurrent hepatic arterial fluorodeoxyuridine (HA FUdR). Patients were evaluated for RILD 2 and 4 months after the completion of treatment. RESULTS: Twenty-one patients completed treatment and were followed up for at least 3 months. The mean dose delivered by the current protocol was 56.6 +/- 2.31 Gy (range, 40.5 to 81 Gy). This dose was significantly greater than the dose that would have been prescribed by the previous protocol (46.0 +/- 1.65 Gy; range, 33 to 66 Gy; P < .01). These data are consistent with H1. One of 21 patients developed RILD. The complication rate of 4.8% (95% confidence interval, 0% to 23.8%) did not differ significantly from the predicted 8.8% NTCP (based on dose delivered) and excluded a 25% true incidence rate (P < .05). This finding supports H2. CONCLUSION: Our results suggest that an NTCP model can be used prospectively to safely deliver far greater doses of radiation for patients with intrahepatic cancer than with previous approaches. Although the observed complication probability is within the confidence intervals of our model, it is possible that this model overestimates the risk of complication and that further dose escalation will be possible. Additional follow-up and accrual will be required to determine if these higher doses produce further improvements in response and survival.     

Multiple-wavelength integration in InGaAs-InGaAsP structures using pulsed laser irradiation-induced quantum-well intermixing

In this paper, we present the characteristics of a quantum-well intermixing technique using pulsed-photoabsorption-induced disordering. Photoluminescence, micro-Raman spectroscopy, and transmission electron microscopy were used to characterize the process. Using this technique, a differential wavelength shift between the intermixed and nonintermixed regions of over 160 nm has been observed from InGaAs-InGaAsP heterostructures. It was found from the micro-Raman measurements that a spatial resolution of better than 2.5 /spl mu/m can be achieved. A theoretical model has been developed to estimate the spatial resolution limit. Theoretical analysis has also been performed to investigate the effect of laser irradiation on the degree of intermixing in InGaAs-InGaAsP structures. To verify the capability of this process in monolithic photonic integration, high-quality bandgap tuned lasers, two-section extended cavity lasers, and multiple-wavelength laser chips have been fabricated.