Improving hydrophobicity on polyurethane-based synthetic leather through plasma polymerization for easy care effect

This study reports on the deposition of a hydrophobic coating on polyurethane (PU)-based synthetic leather through a plasma polymerization method and investigates the hydrophobic behavior of the plasma-coated substrate. The silicon compound of hexamethyldisiloxane (HMDSO), inactive gas argon (Ar), and toluene were used to impart surface hydrophobicity to a PU-based substrate. Surface hydrophobicity was analyzed by water contact angle measurements. Surface hydrophobicity was increased by deposition of compositions of 100% HMDSO, 3:1 HMDSO/toluene, and 1:1 HMDSO/toluene. Optimum conditions of 40 W, 30 s plasma treatment resulted in essentially the same initial contact angle results of approximately 100° for all three treatment compositions. The initial water contact angle for untreated material was about 73°. A water droplet took 1800 s to spread out on the plasma-treated sample after it had been placed on the sample surface. An increase in plasma power also led to a decrease in contact angle, which may be attributed to oxidization of HMDSO during plasma deposition. XPS analysis showed that plasma polymerization of HMDSO/toluene compositions led to a significant increase in atomic percentage of Si compound responsible for the hydrophobic surface. The easy clean results for the treated and untreated PU-based synthetic leather samples clearly showed that the remaining stain on the plasma-polymerized sample was less than that of untreated sample. The plasma-formed coating was both hydrophobic and formed a physical barrier against water and stain.     

The effects of alternating current electrocoagulation on dye removal from aqueous solutions

The main goal of this study is to investigate the effects of alternating current (AC) on dye removal from aqueous solutions by electrocoagulation (EC). An EC system with parallel-connected aluminium electrodes was operated in batch mode. Two different aqueous dye solutions were used: one was obtained from Dianix Yellow CC (DY) and the other was obtained using Procion Yellow (PY). The experiments employing direct current (DC) were carried out using a DC power supply. The AC experiments were conducted using rectangular wave, which is produced with an adjustable time relay connected to the output of DC power supply. This current is called alternating pulse current (APC) in order to refer AC system in this study. Total organic carbon (TOC) and dye removal efficiencies were measured to assess treatment efficiency. Operating cost was calculated for both power supply systems and alternating pulse current was found superior to direct current for the treatment of reactive and disperse dyes used in this study.     

Comparison of one-dimensional and multi-dimensional models in stability analysis of turning operations

Chatter is one of the main problems in machining resulting in poor surface quality and low productivity. Chatter can be avoided by applying stability diagrams which are generated using stability models. The stability analysis of turning has mostly been performed using single dimensional, so-called oriented transfer function approach whereas the actual turning processes usually involve multi-dimensional dynamics. In this paper, a comparative analysis between one dimensional (1D) and multi-dimensional stability models is given for turning operations. The multi dimensional model includes the inclination and side edge cutting angles and insert nose radius in order to demonstrate their effect on absolute stable depth of cut predictions. Chatter experiments are conducted in order to compare with both model predictions. It is demonstrated that for higher inclination angles and insert nose radii 1D models result in significant errors, and multi-dimensional solutions are required.     

Multi-radio diversity in wireless networks

This paper describes the Multi-Radio Diversity (MRD) wireless system, which uses path diversity to improve loss resilience in wireless local area networks (WLANs). MRD coordinates wireless receptions among multiple radios to improve loss resilience in the face of path-dependent frame corruption over the radio. MRD incorporates two techniques to recover from bit errors and lower the loss rates observed by higher layers, without consuming much extra bandwidth. The first technique is frame combining, in which multiple, possibly erroneous, copies of a given frame are combined together in an attempt to recover the frame without retransmission. The second technique is a low-overhead retransmission scheme called request-for-acknowledgment (RFA), which operates above the link layer and below the network layer to attempt to recover from frame combining failures. We present an analysis that determines how the parameters for these algorithms should be chosen. We have designed and implemented MRD as a fully functional WLAN infrastructure based on 802.11a. We evaluate the MRD system under several different physical configurations, using both UDP and TCP, and measured throughput gains up to 3× over single radio communication schemes employing 802.11’s autorate adaptation scheme. Computer and Communication Sciences, EPFL, Switzerland. Allen Miu received his Ph.D. degree at the Massachusetts Institute of Technology in 2006 and is currently a wireless systems architect at Ruckus Wireless, Inc. He received his S.M. in Computer Science from MIT and a B.Sc. with highest honors in Electrical Engineering and Computer Science from the University of California at Berkeley. He previously worked on the Cricket Indoor Location System and was a research intern at Microsoft Research, Redmond in 2000 and Hewlett-Packard Laboratories, Palo Alto in 2002. His research interests include wireless networks, location systems, mobile computing, and embedded systems. Hari Balakrishnan is an Associate Professor in the EECS Department and a member of the Computer Science and Artificial Intelligence Laboratory (CSAIL) at MIT. His research interests is in the area of networked computer systems. In addition to many widely cited papers, several systems developed as part of his research are available in the public domain. He received a Ph.D. in Computer Science from the University of California at Berkeley in 1998 and a B.Tech. from the Indian Institute of Technology (Madras) in 1993. His honors include an Alfred P. Sloan Research Fellowship (2002), an NSF CAREER Award (2000), the ACM doctoral dissertation award for his work on reliable data transport over wireless networks (1998), and seven award-winning papers at various top conferences and journals, including the IEEE Communication Society’s William R. Bennett Prize (2004). He has also received awards for excellence in teaching and research at MIT (Spira, Junior Bose, and Harold Edgerton faculty achievement awards). C. Emre Koksal received his B.S. degree in Electrical Engineering from the Middle East Technical University, Ankara in 1996. He received his S.M. and Ph.D. degrees from MIT in Electrical Engineering and Computer Science in 1998 and 2002 respectively. He was a postdoctoral fellow in the Networks and Mobile Systems Group in the Computer Science and Artificial Intelligence Laboratory at MIT until 2003. Since then he has been a senior researcher jointly in the Laboratory for Computer Communications and the Laboratory for Information Theory at EPFL, Switzerland. His general areas of interest are wireless communications, computer networks, information theory, stochastic processes and financial economics. He also has a certificate on Financial Technology from the Sloan School of Management at MIT.     

The effect of par‐baking and frozen storage time on the quality of cup cake

The effects of frozen storage and initial baking time of par‐baked cake on baking loss, volume, moisture, colour and textural properties of cake obtained after thawing and rebaking were investigated. Cakes, par‐baked at 175 °C for 15, 20 and 25 min, were stored at ?18 °C for 3, 6 and 9 months. After storage, par‐baked cakes were thawed and rebaked at 175 °C for 10, 15 and 20 min. Baking loss, moisture content, L and +b colour values, firmness, gumminess and chewiness of the resulting full‐baked cakes were significantly affected by both par‐baking and frozen storage time, while specific volume, cohesiveness, springiness and resilience values were significantly affected by frozen storage time. The increase in the time of frozen storage of the par‐baked cake leads to a decrease in the quality of the rebaked cake, namely an increase of baking loss and cake crumb firmness, and a loss in the moisture content and specific volume. Moisture of cake crumb, L and +b colour values, firmness, gumminess and chewiness significantly increased as the par‐baking time increased. However, regarding baking loss, specific volume, moisture content and textural properties, 3‐month intermediate storage at ?18 °C and 20‐min initial baking time gave the best result among the cakes produced by using the two‐step baking procedure.     

Preparation of Lead Zirconate by Homogeneous Precipitation and Calcination

Antiferroelectric PbZrO₃ has been synthesized by homogeneous precipitation from aqueous solutions in the presence of urea (NH₂CONH₂) and calcination for 6 h at 700°C. SEM studies displayed the presence of submicrometer powder, with a significant degree of agglomeration.     

A Benchmark for Some Physical Properties of Zinc-Blende ZnS

Somephysical properties of zinc-blende polytype of ZnS were investigated via geometry optimization calculations. After employing a shell model interatomic potential to our computations, some physical parameters such as typical cubic elastic constants, young modulus, shear modulus, bulk modulus, poisson ratio, elastic wave velocities, static and high frequency dielectric constants, and static refractive index zinc-blende ZnS were deduced. Later, previous theoretical results and our current results with each other as well as with former experimental findings were evaluated. Present results exhibit a fair consistency with experiments and better than those of several recent density functional theory results for the considered parameters of related material.     

Optimal regulation of homogeneous systems

We present an offline numerical algorithm to generate a discontinuous feedback law to robustly regulate the origin of a continuous-time homogeneous system through sample and hold. The proposed feedback comes out of the solution of an infinite horizon optimization problem in discrete time and is in the form of a look-up table. We show that when applied to either chained systems or systems in power form the algorithm results in a closed loop whose origin is globally exponentially stable.