MODELING LIQUID MASS TRANSFER IN HIGEE SEPARATION PROCESS

Correspondence concerning this paper should be addressed to Professor Richard S.H. Mah. Hsien-Hsin Tung is now affiliated with Department of Chemical Engineering, California Institute of Technology

Penetration theory is used to describe the liquid mass transfer in Higee separation process. Within a possible range of effective areas, it is shown that the predicted mass transfer coefficients are in reasonable agreement with the estimated mass transfer coefficients. The estimated coefficients were calculated from the experimental data and the possible effective areas. Hence it is concluded the penetration theory is generally applicable to describe liquid mass transfer in Higee separation process. The comparison also suggests that liquid mixing at the junctions of packing materials may be more complete in Higee process than in traditional process.     

揭秘IT白领生存之道：巧妙用面子赚钞票

翻盖手机为什么受欢迎 你知道翻盖手机为什么在东北亚地区尤其是中国流行吗？恐怕很少有人想到,原因之一是与中国人爱面子有关系。     

Analysis of the Optimum Configuration of Roadside Units and Onboard Units in Dedicated Short-Range Communication Systems

With the aid of a simple relation, which is analogous to the radar equation, the uplink signal strength received by the receiving module of a roadside unit (RSU) and emitted from the radiation module of an onboard unit (OBU) can be described. Setting the scale of this relation arbitrarily and determining the signal strength threshold from experimental measurements, and combined with the simulation of the radiation and the receiving pattern by cosineⁿ function, the relative signal strength emitted from the OBU and received by the RSU can be calculated successfully. From this computed relative signal strength and the threshold, the influence of the RSU and OBU mounting parameters, such as the mounting angles and mounting height, on the available communication region is analyzed. The effect of windshield fading is also considered. With the help of the analysis results, an optimum RSU and OBU mounting configuration can be easily obtained. This method can be used conveniently and successfully for very short wavelengths. This includes visible light, infrared, and even submillimeter-wave ranges. For millimeter-wave and microwave systems, this method can, in some cases, also provide a rudimentary estimation     

Association of Ligamentum Flavum Hypertrophy with Adolescent Idiopathic Scoliosis Progression—Comparative Microarray Gene Expression Analysis

The role of the ligamentum flavum (LF) in the pathogenesis of adolescent idiopathic scoliosis (AIS) is not well understood. Using magnetic resonance imaging (MRI), we investigated the degrees of LF hypertrophy in 18 patients without scoliosis and on the convex and concave sides of the apex of the curvature in 22 patients with AIS. Next, gene expression was compared among neutral vertebral LF and LF on the convex and concave sides of the apex of the curvature in patients with AIS. Histological and microarray analyses of the LF were compared among neutral vertebrae (control) and the LF on the apex of the curvatures. The mean area of LF in the without scoliosis, apical concave, and convex with scoliosis groups was 10.5, 13.5, and 20.3 mm², respectively. There were significant differences among the three groups (p < 0.05). Histological analysis showed that the ratio of fibers (Collagen/Elastic) was significantly increased on the convex side compared to the concave side (p < 0.05). Microarray analysis showed that ERC2 and MAFB showed significantly increased gene expression on the convex side compared with those of the concave side and the neutral vertebral LF cells. These genes were significantly associated with increased expression of collagen by LF cells (p < 0.05). LF hypertrophy was identified in scoliosis patients, and the convex side was significantly more hypertrophic than that of the concave side. ERC2 and MAFB genes were associated with LF hypertrophy in patients with AIS. These phenomena are likely to be associated with the progression of scoliosis.     

A no-tension elastic–plastic model and optimized back-analysis technique for modeling nonlinear mechanical behavior of rock mass in tunneling

In this paper, we present a no-tension elastic–plastic model and an optimized back-analysis technique for stability analysis of underground tunnels. A set of constitutive equations is presented to simulate the no-tension behavior and plastic yielding of jointed rock masses which yield according to the Drucker–Prager yield criterion and permits no-tension. A nonlinear 2-D finite element model is consequently formulated for the prediction of the behavior of the excavated rock mass. As for the model parameters, the genetic algorithm technique is employed to find the optimal rock mass properties by minimizing the discrepancy between the predicted results and field measurement. The nonlinear finite element model coupling with the genetic algorithm optimized back-analysis technique is then applied to a synthetic example of a deep tunnel in yielding rock. The results show that the forward and back-analysis system is capable of estimating the model parameters with stable and good convergence and give reasonable predictions. Numerical experiments are also carried out to check the influences of position and numbers of measurements to the reliability of the back-analysis results. Furthermore, the sensitivity analysis of the genetic algorithms optimization procedure is discussed in terms of identification of geo-material properties.     

A novel energy‐retaining inverter for AC arc welding machines

A novel energy‐retaining power supply for AC arc welding machines is proposed in this paper. In this kind of power supply, current‐steering diodes connected across the output chokes keep the inductor current continuous and retain the energy during the commutation period, hence reducing the commutation time to ensure a better welding performance. In addition, the stored energy can be released in the next energy transfer cycle to raise the conversion efficiency. The circuit operations and design procedures are likewise examined thoroughly. Experimental results on a prototype inverter for driving a 100‐A AC arc welding machine are recorded to validate the effectiveness of the presented scheme. Copyright © 2010 John Wiley & Sons, Ltd.     

Lithium-Ion Desolvation Induced by Nitrate Additives Reveals New Insights into High Performance Lithium Batteries

Electrolyte additives have been widely used to address critical issues in current metal (ion) battery technologies. While their functions as solid electrolyte interface forming agents are reasonably well-understood, their interactions in the liquid electrolyte environment remain rather elusive. This lack of knowledge represents a significant bottleneck that hinders the development of improved electrolyte systems. Here, the key role of additives in promoting cation (e.g., Li⁺) desolvation is unraveled. In particular, nitrate anions (NO₃⁻) are found to incorporate into the solvation shells, change the local environment of cations (e.g., Li⁺) as well as their coordination in the electrolytes. The combination of these effects leads to effective Li⁺ desolvation and enhanced battery performance. Remarkably, the inexpensive NaNO₃ can successfully substitute the widely used LiNO₃ offering superior long-term stability of Li⁺ (de-)intercalation at the graphite anode and suppressed polysulfide shuttle effect at the sulfur cathode, while enhancing the performance of lithium–sulfur full batteries (initial capacity of 1153 mAh g⁻¹ at 0.25C) with Coulombic efficiency of ≈100% over 300 cycles. This work provides important new insights into the unexplored effects of additives and paves the way to developing improved electrolytes for electrochemical energy storage applications.     

A Multicell Linear Power Amplifier for Driving Piezoelectric Loads

A multicell amplifier is developed by connecting floating signal modules in series to drive piezoelectric devices. The amplifier generates a high voltage gain by summing the individual module gains. The bandwidth equals that of a single module. The multicell amplifier provides a means of achieving high power and can divide the total power dissipation among the modules, because each module delivers the same output voltage and current. A prototype circuit that consists of six floating signal modules exhibits precise linear operation over a wide range of input frequencies and capacitive loads. The circuit provides a plusmn 200-V output swing with a corner frequency of around 100 kHz at a driving capacitive load of 0.1 muF. The slew rate is as high as 115 V/mus, and the maximum output current is plusmn2.6 A. The practicality and performance of the presented modular implementation concepts were verified by the close match between the simulated and experimental results.     

High-performance fully depleted silicon nanowire (diameter /spl les/ 5 nm) gate-all-around CMOS devices

This paper demonstrates gate-all-around (GAA) n- and p-FETs on a silicon-on-insulator with /spl les/ 5-nm-diameter laterally formed Si nanowire channel. Alternating phase shift mask lithography and self-limiting oxidation techniques were utilized to form 140- to 1000-nm-long nanowires, followed by FET fabrication. The devices exhibit excellent electrostatic control, e.g., near ideal subthreshold slope (/spl sim/ 63 mV/dec), low drain-induced barrier lowering (/spl sim/ 10 mV/V), and with I/sub ON//I/sub OFF/ ratio of /spl sim/10/sup 6/. High drive currents of /spl sim/ 1.5 and /spl sim/1.0 mA//spl mu/m were achieved for 180-nm-long nand p-FETs, respectively. It is verified that the threshold voltage of GAA FETs is independent of substrate bias due to the complete electrostatic shielding of the channel body.