Pipe failure rate prediction in water distribution networks using multivariate adaptive regression splines and random forest techniques

ABSTRACT

This paper presents the results of a comparison between multivariate adaptive regression splines (MARS) and random forest (RF) techniques in pipe failure prediction in two water distribution networks. In this regard, pipe diameter, pipe length, pipe installation depth, pipe age and average hydraulic pressure are considered as input variables. Results show that the RF outperforms the MARS which is found as an accurate pipe failure rate predictor. The proposed models are further evaluated through dividing the data into three parts of lower, medium and higher pipe failure rate values. According to the equations produced by MARS technique, three variables of pipe diameter, pipe age and average hydraulic pressure are distinguished as the most effective variables in predicting pipe failure rate in the first case study. Four variables of pipe diameter, pipe length, pipe age and average hydraulic pressure are determined as the most effective variables in the second case study.     

An investigation of the flocculation characteristics of polyacrylamide‐grafted chitosan

To investigate the flocculation characteristics of polyacrylamide (PAM)‐grafted chitosan, a series of PAM‐grafted chitosan copolymer (Chito‐g‐PAM1 to Chito‐g‐PAM4) have been synthesized by ceric ammonium nitrate‐induced solution polymerization technique in nitrogen atmosphere. The flocculation characteristics of the polymer samples (PAM, grafted and ungrafted chitosan) were studied by settling test and jar test methods in the colloidal suspensions of kaolin, iron ore, silica, and bentonite powder. It was found that the settling performance of Chito‐g‐PAM3 is best among the polymer samples. The jar test results indicate that the ungrafted chitosan has better water clarifying performance than both the PAM and grafted chitosan. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

基于电话语料的维吾尔连续音素识别

结合维吾尔语的语音特征和语义信息,在大量电话语音语料库的基础上,以建立维吾尔语连续音素识别平台为目标,通过构建隐马尔科夫模型工具HTK(Hidden Markov Model Toolkit)工具实现了维吾尔语连续音素识别算法:首先根据具体技术指标完成了较大规模电话语音语料库的录制和标注工作;确定音素为基元,通过训练获得了每个音素的HMM(Hidden Markov Model)声学模型,随后对输入的语音进行识别,声学模型在不同的高斯混合数目下,得出了识别结果;统计了32个音素的识别率并对它进行分析,为了进一步提高识别率奠定了基础。     

A Bulk‑Heterostructure Nanocomposite Electrolyte of Ce0.8Sm0.2O2‑δ-SrTiO3 for Low‑Temperature Solid Oxide Fuel Cells

Since colossal ionic conductivity was detected in the planar heterostructures consisting of fluorite and perovskite,heterostructures have drawn great research interest as potential electrolytes for solid oxide fuel cells(SOFCs).However,so far,the practical uses of such promising material have failed to materialize in SOFCs due to the short circuit risk caused by SrTiO3.In this study,a series of fluorite/perovskite heterostructures made of Sm-doped CeO2 and SrTiO3(SDC–STO)are developed in a new bulk-heterostructure form and evaluated as electrolytes.The prepared cells exhibit a peak power density of 892 mW cm−2 along with open circuit voltage of 1.1 V at 550°C for the optimal composition of 4SDC–6STO.Further electrical studies reveal a high ionic conductivity of 0.05–0.14 S cm^−1 at 450–550°C,which shows remarkable enhancement compared to that of simplex SDC.Via AC impedance analysis,it has been shown that the small grain-boundary and electrode polarization resistances play the major roles in resulting in the superior performance.Furthermore,a Schottky junction effect is proposed by considering the work functions and electronic affinities to interpret the avoidance of short circuit in the SDC–STO cell.Our findings thus indicate a new insight to design electrolytes for low-temperature SOFCs.     

Synthesis,characterization and thermal behaviors of polymers containing organosilicon groups

Various bis(silyl)ethenyl groups were attached to the aromatic ring of poly(α-methylstyrene) via Peterson olefination reaction of (RMe₂Si)₃CLi (R = H, Me and Ph) with formylated poly(α-methylstyrene) (Pα-MS-CHO) to give poly(α-methylstyrene)-co-[2,2-bis(silyl)ethenyl(α-methylstyrene)] as functionalized poly(α-methylstyrene) (Pα-MS-SiMe₂H, Pα-MS-SiMe₃ and Pα-MS-SiMe₂Ph). The trimethylsilyl groups of Pα-MS-SiMe₃ have been converted to 2,2-dibromoethenyl and epoxybis(silanes) groups via NBS-based bromodesilylation and MCPBA-based epoxidation respectively. The thermal degradation behaviors of the polymers were studied using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC).     

Practical evaluation of relationship between concrete resistivity,water penetration,rapid chloride penetration and compressive strength

There are several factors and test methods for evaluating the durability of concrete. In recent years a great deal of attention has been paid to research and development of relationships of these parameters for production of sustainable concretes: water penetration and Rapid Chloride Penetration Test (RCPT) methods which are most commonly used to evaluate the permeability of concrete are two of the most famous methods specified by BS EN-12390-8:2000 and ASTM C1202 respectively. Concrete surface resistivity (SR) test is also a suitable indicator for concrete penetration and chloride ion permeability. It is a non-destructive, simple, rapid and economical method that can also be used on site.The present study is an exploratory research concerned with the relationship of these methods. Based on the correlation of concrete resistivity with water penetration and Rapid Chloride Penetration Test (RCPT) results, two new models for relating these parameters are presented.     

Curcumin and Liver Disease: from Chemistry to Medicine

Curcumin, the natural yellow‐colored active principle, also called turmeric yellow, extracted from the perennial herb Curcuma longa L., has potent biological and pharmacological properties such as antioxidant, anti‐inflammatory, antifungal, antibacterial, anti‐ischemic, antitumor, and anticancer actions. The molecular mechanism of the hepatoprotective action of curcumin is due to its antioxidant properties and inhibitory activity against nuclear factor (NF)‐κB that regulates different proinflammatory and profibrotic cytokines. Overall, scientific reports demonstrate that curcumin has high therapeutic ability for treating hepatic disorders. Here is a systematic discussion of the hepatoprotective activity of curcumin and its possible mechanisms of actions.     

A Flat Polymeric Membrane Sensor for Carbon Dioxide/Nitrogen Gas Mixture

A gas sensor was developed to measure the concentration of binary gas mixtures. This sensor works based on the permeability change of different gas mixtures across the polymeric membranes. Although high values of permeability and selectivity are needed for an ideal separation, the performance of this sensor mainly depends on the permeability factor. Polysulfone and silicone rubber were applied as the membrane base and coat, respectively. Moreover, in contrast to existing polymeric sensors that use hollow fibers, the present sensor is made of flat membranes. This new design is cheaper, smaller, and easier to use in comparison to the hollow fiber polymeric sensors. In order to test the sensor applicability, nitrogen and carbon dioxide were used as model gases. The effect of pressure on the response time and sensor accuracy was studied for the aforementioned gases. The response time (T_95%) of this low price sensor was 50?s, and the tolerance of measuring concentration was approximately 1.4% at 2?bar feed pressure. Also, increasing the feed pressure can improve the response time or accuracy of the sensor.     

Schauder fixed point theorem based existence of periodic solution for the response of Duffing’s oscillator

An initial-boundary value problem that is Duffing’s oscillator with time varying coefficients will be studied. Using Banach’s fixed-point theorem, the existence of periodic solution of the equation will be predicted. The method applied in this paper is the Schauder second fixed point theorem, which includes the response of structures under vibratory force systems. As an example, the dynamics of nonlinear simply supported rectangular thin plate under influence of a relatively moving mass is studied. By expansion of the solution as a series of mode functions, the governing equations of motion are reduced to an ordinary differential equation for time development vibration amplitude, which is Duffing’s oscillator. Finally, a parametric study is developed, after that some numerical examples are solved, and the validity of the present analysis is clearly shown. This paper was recommended for publication in revised form by Associate Editor Maenghyo Cho Hossein Ali Sepiani received his B.S. degree in Mechanical Engineering from University of Kashan, Iran, in 2003. He then received his M.S. degree from University of Tehran, in 2006. Currently, Hossein is continuing his research at University of Tehran. His research interests include new materials (FGMs, Nano-materials, SMAs, SMPs, etc), Composites (Woven Fabrics and Fiber Metal Laminates), Smart Materials (Shape Memory Alloy, Magnet/Electro-rheological and Piezoelectric Sensors and Actuators), Intelligent structures (Structures integrated with smart materials), Vibration and control of Intelligent Structures and their application. Ahmad Feyz Dizaji got his B.S. degree from University of Tehran, Iran, in 1970. Then he continued his study in U.S. and received his PhD. degree from Michigan State University in 1983, in Applied Mathematics under the supervision of Professor Shui-ni Chow and Professor J. Mallet-Paret. Since then he has been a member of the Faculty of Engineering in University of Tehran, teaching mathematics in both undergraduate and graduate levels.