Asphalt concrete rutting predicted using the PEDRO model

This paper presents a theoretical viscoelastic approach, called PEDRO (PErmanent Deformation of asphalt concrete layers for ROads), for predicting rut formation in asphalt concrete materials subjected to traffic loading. Input data are traffic parameters, asphalt concrete viscosity and asphalt layer thickness. Vertical strains that cause rutting in the pavement were estimated using the PEDRO approach. A large-size type of wheel tracking machine, which has the capability to subject asphalt concrete slabs to different loadings, has been used to study the effects of wheel load and tyre pressure. Rut development in the slabs under various loading conditions was predicted. The approach has shown reasonable results as regards predicting densification and shear rutting in the tested asphalt concrete slabs.     

MPTCP与CMT-SCTP多路径传输协议性能分析

利用终端的多宿主特性实现多路径传输是因特网协议的一个热点研究问题,MPTCP和CMT-SCTP是目前比较成熟而关键的两个多路径传输协议,但在大规模应用前还需要作大量的性能测试分析研究。在本地测试床环境中,对MPTCP和CMT-SCTP多路径传输实际吞吐量的性能进行对比测试与分析。结果表明MPTCP和CMT-SCTP都能获得吞吐量的提高,但传输调度算法仍然不完善,需要进一步改进。     

Solving the circular open dimension problem by using separate beams and look-ahead strategies

In this paper, a constructive method is investigated for solving the circular open dimension problem (CODP), a problem of the Cutting and Packing family. CODP is a combinatorial optimization problem which is characterized by a set of circular pieces of known radii and a strip of fixed width W and unlimited length. The objective is to determine the smallest rectangle of dimensions (L, W), where L is the length of the rectangle, that will contain all the pieces such that there is no overlapping between the placed pieces and all the demand constraints are satisfied. The method combines the separate-beams search, look-ahead, and greedy procedures. A study concerning both restarting and look-ahead strategies is undertaken to determine the best tuning for the method. The performance of the method is computationally analyzed on a set of instances taken from the literature and for which optimal solutions are not known. Best-known solutions are obtained.     

www.rnaworkbench.com: A new program for analyzing RNA interference

RNA interference (RNAi) has become an important tool to study and utilize gene silencing by introducing short interfering RNA (siRNA). In order to predict the most efficient siRNAs, a new software tool, RNA Workbench (RNAWB), has been designed and is freely available (after registration) on http://www.rnaworkbench.com. In addition to the standard selection rules, RNAWB includes the possibility of statistical analyses of the applied selection rules (criteria). The role of RNA secondary structures in the RNA interference process as well as the application of sequence rules are discussed to show the applicability of the software.     

Effect of Ultraviolet Radiation on the Mechanical and Dielectric Properties of Hessian Cloth/PP Composites with Starch

Hessian cloth (jute fabrics) reinforced poly(propylene) (PP) composites (45 wt% fiber) were prepared by compression molding and the mechanical properties were evaluated. Jute fabrics and PP sheets were treated with UV radiation at different intensities and then composites were fabricated. It was found that mechanical properties of the irradiated jute and irradiated PP-based composites were found to increase significantly compared to that of the untreated counterparts. Irradiated jute fabrics were also treated with aqueous starch solution (1–5%, w/w) for 2–10 min. Composites made of 3% starch-treated jute fabrics (5 min soaking time) and irradiated PP showed the best mechanical properties. Tensile strength, bending strength, tensile modulus, bending modulus and impact strength of the composites were found to improve 31, 41, 42, 46 and 84% higher over untreated composites. Water uptake, thermal degradation and dielectric properties of the resulting composites were also performed.     

Signal-to-noise ratio for lightwave systems using avalanchephotodiodes

An expression for the signal-to-noise ratio (SNR) at the output of an avalanche photodiode (APD) receiver is derived that includes the effects of photoinjected carriers, dark-generated carriers, and the receiver circuitry. It is found that the dark current alters both the magnitude of the SNR and the value of the mean multiplication where the SNR achieves its maximum value. The formula differs from the expression that is conventionally used (S.M. Sze, 1981) in that it makes use of different excess noise factors for photo-generated and dark-generated carriers     

A computer program for the optimization of the machining variables

In practice, the values of the machining variables (cutting speed, feed and depth of cut) are determined either by mere experience as usually done by machine tool operators or selected from the available engineering tables which is the usual practice for engineers and technologists. Both methods do not take the process constraints into consideration and merely depend on the personal experience of the employed personnel and hence lead to values which are too far from the economic values. The present paper present a technological optimization technique for turning operations. A computer program has been developed for this purpose, by means of which those optimum values of the machining variables can be obtained, which satisfy the encountered technical and technological constraints and lead to minimum manufacturing cost or maximum production rate as required.     

Relationships between teachers' presentations of classroom tasks and students' engagement in those tasks.

Correlated the presence/absence of various teacher task-presentation statements with measures of subsequent student task engagement to investigate the possibility that expectations about classroom tasks that teachers communicate to students in the process of presenting those tasks might affect student engagement in the tasks. Reading and math lessons were observed (8–25 times each) in 2 4th-grade, 2 5th-grade, and 2 6th-grade classes. Typically, each reading or math period was subdivided into 2–4 tasks. For example, a math period might begin with a review of the previous day's seatwork/homework assignment, followed by presentation of a new concept or skill, followed by presentation of a new assignment. Teacher-presentation data and student-engagement data were collected for each task observed. Contrary to expectation, student engagement was generally higher when teachers moved directly into tasks than when they began with some presentation statement. Within the subset of tasks that were begun with teacher-presentation statements, those presentation statements classified as likely to have negative effects on student engagement were associated with lower student engagement, but there was no corresponding tendency for teacher-presentation statements classified as likely to have positive effects on student engagement to be associated with high rates of student engagement. (11 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)