Ultra Low-Dose Radiation: Stress Responses and Impacts Using Rice as a Grass Model

We report molecular changes in leaves of rice plants (Oryza sativa L. - reference crop plant and grass model) exposed to ultra low-dose ionizing radiation, first using contaminated soil from the exclusion zone around Chernobyl reactor site. Results revealed induction of stress-related marker genes (Northern blot) and secondary metabolites (LC-MS/MS) in irradiated leaf segments over appropriate control. Second, employing the same in vitro model system, we replicated results of the first experiment using in-house fabricated sources of ultra low-dose gamma (γ) rays and selected marker genes by RT-PCR. Results suggest the usefulness of the rice model in studying ultra low-dose radiation response/s.     

Heat pipe based cold energy storage systems for datacenter energy conservation

In the present paper, design and economics of the novel type of thermal control system for datacenter using heat pipe based cold energy storage has been proposed and discussed. Two types of cold energy storage system namely: ice storage system and cold water storage system are explained and sized for datacenter with heat output capacity of 8800 kW. Basically, the cold energy storage will help to reduce the chiller running time that will save electricity related cost and decrease greenhouse gas emissions resulting from the electricity generation from non-renewable sources. The proposed cold energy storage system can be retrofit or connected in the existing datacenter facilities without major design changes. Out of the two proposed systems, ice based cold energy storage system is mainly recommended for datacenters which are located in very cold locations and therefore can offer long term seasonal storage of cold energy within reasonable cost. One of the potential application domains for ice based cold energy storage system using heat pipes is the emergency backup system for datacenter. Water based cold energy storage system provides more compact size with short term storage (hours to days) and is potential for datacenters located in areas with yearly average temperature below the permissible cooling water temperature (∼25 °C). The aforesaid cold energy storage systems were sized on the basis of metrological conditions in Poughkeepsie, New York. As an outcome of the thermal and cost analysis, water based cold energy storage system with cooling capability to handle 60% of datacenter yearly heat load will provide an optimum system size with minimum payback period of 3.5 years. Water based cold energy storage system using heat pipes can be essentially used as precooler for chiller. Preliminary results obtained from the experimental system to test the capability of heat pipe based cold energy storage system have provided satisfactory outcomes and validated the proposed system concept.     

Analysis of bandwidth allocation algorithms for wireless personal area networks

A major issue in the design and operation of ad hoc networks is sharing the common spectrum among links in the same geographic area. Bandwidth allocation, to optimize the performance of networks in which each station can converse with at most a single neighbor at a time, has been recently studied in the context of Bluetooth Personal Area Networks. There, centralized and distributed, capacity assignment heuristics were developed, with applicability to a variety of ad hoc networks. Yet, no guarantees on the performance of these heuristics have been provided. In this paper, we extend these heuristics such that they can operate with general convex objective functions. Then, we present our analytic results regarding these heuristics. Specifically, we show that they are β-approximation (β<2) algorithms. Moreover, we show that even though the distributed and centralized algorithms allocate capacity in a different manner, both algorithms converge to the same results. Finally, we present numerical results that demonstrate the performance of the algorithms. Randeep Bhatia received the Ph.D. degree in Computer Science from University of Maryland, the M.S. degree in Mathematics and Computer Science from University of Illinois at Chicago and the B.Tech. degree in Computer Science and Engineering from Indian Institute of Technology, Delhi. He is currently with the High Speed Networks Research Department at Bell Labs, Lucent technologies, working on network design, traffic engineering and scheduling algorithms. His current research interests are in the area of QoS for multimedia services in wireless data networks. Adrian Segall received the B.Sc. and M.Sc. degrees in electrical engineering from the Technion, Israel Institute of Technology in 1965 and 1971, respectively, and the Ph.D. degree in electrical engineering with a minor in statistics from Stanford University in 1973. After serving active duty in the Israel Defense Forces, he joined in 1968 the Scientific Department of Israel’s Ministry of Defense. From 1973 to 1974 he was a Research Engineer at System Control Inc., Palo Alto, CA and a Lecturer at Stanford University. From 1974 to 1976 he was an Assistant Professor of Electrical Engineering and Computer Science at the Massachusetts Institute of Technology. From 1987 to 1998 he was on the faculty of the Department of Computer Science at the Technion. He is presently Benjamin Professor of Computer-Communication Networks in the Department of Electrical Engineering, Technion, Israel Institute of Technology. From 1982 to 1984 he was on leave with the IBM T.J.Watson Research Center, Yorktown Heights, NY. He held visiting positions with IBM, AT&T and Lucent Bell Labs. His current research interests are in the area of optical networks, wireless, sensor and ad-hoc networks. Dr. Segall is an IEEE Fellow and has served in the past as Editor for Computer Communication Theory of the IEEE Transactions on Communications, Editor for the IEEE Information Theory Society Newsletter and Senior Editor for the IEEE Journal on Selected Areas in Communications. He was selected as an IEEE delegate to the 1975 IEEE-USSR Information Theory Workshop, and is the recipient of the 1981 Miriam and Ray Klein Award for Outstanding Research and of the 1990 Taub Award in Computer Science. Gil Zussman received the B.Sc. degree in Industrial Engineering and Management and the B.A. degree in Economics (both summa cum laude) from the Technion—Israel Institute of Technology in 1995. He received the M.Sc. degree (summa cum laude) in Operations Research from Tel-Aviv University in 1999 and the Ph.D. degree in Electrical Engineering from the Technion—Israel Institute of Technology in 2004. Between 1995 and 1998, he served as an engineer in the Israel Defense Forces. He is currently a Postdoctoral Associate in the Laboratory for Information and Decision Systems in MIT. His current research interests are in the area of ad hoc and sensor networks. In particular, he is interested in energy efficient protocols, medium access control protocols, and personal area networks. Gil received the Knesset (Israeli Parliament) Award for distinguished students, the Best Student Paper Award at the IFIP-TC6 Networking 2002 Conference, and the IEEE Communications Magazine Best Paper Award at the OPNETWORK 2002 Conference. In 2004 he received the Marie Curie Outgoing International Fellowship and the Fulbright Fellowship.     

Traffic Engineering of Management Flows by Link Augmentations on Confluent Trees

Service providers rely on the management systems housed in their Network Operations Centers (NOCs) to remotely operate, monitor and provision their data networks. Lately there has been a tremendous increase in management traffic due to the growing complexity and size of the data networks and the services provisioned on them. Traffic engineering for management flows is essential for the smooth functioning of these networks to avoid congestion, which can result in loss of critical data such as billing records, network alarms, etc. As is the case with most intra-domain routing protocols, the management flows in many of these networks are routed on shortest paths connecting the NOC with the service provider’s POPs (points of presence). This collection of paths thus forms a “confluent” tree rooted at the gateway router connected to the NOC. The links close to the gateway router may form a bottleneck in this tree resulting in congestion. Typically this congestion is alleviated by adding layer two tunnels (virtual links) that offload the traffic from some links of this tree by routing it directly to the gateway router. The traffic engineering problem is then to minimize the number of virtual links needed for alleviating congestion. In this paper we formulate a traffic engineering problem motivated by the above mentioned applications. We show that the general versions of this problem are hard to solve. However, for some simpler cases in which the underlying network is a tree, we design efficient algorithms. In particular, we design fully polynomial-time approximate schemes (FPTAS) for different variants of this problem on trees. We use these algorithms as the basis for designing efficient heuristics for alleviating congestion in general (non-tree) service provider network topologies.     

Slicing,cleaning and kerf analysis of germanium wafers machined by wire electrical discharge machining

This paper investigates the slicing of germanium wafers from single crystal, gallium-doped ingots using wire electrical discharge machining. Wafers with a thickness of 350 μm and a diameter of 66 mm were cut using 75 and 100 μm molybdenum wire. Wafer characteristics resulting from the process such as the surface profile and texture are analyzed using a surface profiler and scanning electron microscopy. Detailed experimental investigation of the kerf measurement was performed to demonstrate minimization of material wastage during the slicing process using WEDM in combination with thin wire diameters. A series of timed etches using two different chemical etchants were performed on the machined surfaces to measure the thickness of the recast layer. Cleaning of germanium wafers along with its quality after slicing is demonstrated by using Raman spectroscopy.     

Markov chain reduction and analysis of GSPN models for task allocation in distributed systems

In this paper, we present a Markov chain (MC) reduction technique for analysis of a certain class of MCs. It requires only O(t) steps to analyze an MC having t states by this technique, as compared to O(t³) steps required by the usual matrix inversion method. We also present a generalized stochastic Petri net (GSPN) model for task allocation in distributed computer systems, where execution and inter-module communication costs are treated as random variables with exponential probability distribution. We show that the MC of this task system falls into a class to which the reduction technique is applicable. As an illustration of the reduction technique, we use a GSPN model of the task system to find the mean completion time of the system.     

Operational characteristics of the miniature loop heat pipe with non-condensable gases

The present paper experimentally investigates the effect of non-condensable gases (NCGs) on the thermal performance of the miniature loop heat pipe (mLHP). Copper mLHP with the flat disk shaped evaporator, 30 mm diameter and 10 mm thick, and fin-and-tube type condenser, 50 mm length and 10 mm height, located at a distance of 150 mm was used in the study. The device which was designed for the thermal control of computer microprocessor was capable of transferring maximum heat load of 70 W while maintaining evaporator temperature below 100 °C limit for electronic equipments. Water was used as the heat transfer fluid inside the mLHP. All the tests were conducted with the evaporator and condenser at the same horizontal level. Simple methods were devised to detect and purge the generated NCG out of the loop heat pipe without disassembling the system. Experiments conducted to classify the trends in the NCG production and storage revealed that majority of the gas is generated in the first few thermal runs and is accumulated in the compensation chamber. Sensitivity tests show that overall effect of the NCG is to elevate the steady-state operating temperature of the loop and increase the start-up time required by the evaporator to achieve stable conditions for the given heat load. As an outcomes of the research work, it can be concluded that mLHPs are more tolerable to the NCGs than conventional heat pipes due to the presence of compensation chamber that can accumulate most of the released gas without major performance degradation.     

Role of poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) in the modification of polysulfone membranes for ultrafiltration

In this study polysulfone membranes with antifouling and hydrophilic properties were synthesized using poly(2‐acrylamido‐2‐methyl‐1‐propanesulfonic acid) (AMPS) as an additive for the first time. Different wt % of AMPS was used to prepare polysulfone membranes by phase inversion method. The role of AMPS on the porosity, pore size distribution, hydrophilicity, and antifouling nature was investigated and analyzed in detail. Characterization techniques like field emission scanning electron microscope, atomic force microscopy, and imageJ software were used to characterize the morphology of prepared membranes. There is positive effect of the additive addition on all the membrane parameters like Pure water flux [101.76 L/(m² h)] (MR0) to 464.06 L/(m² h) (MR4)], hydraulic permeability [0.65 (MR0) to 2.01 (MR4)], equilibrium water content [21.74 (MR0) to 71.45 (MR4)], and porosity [0.024 (MR0) to 0.58 (MR4)]. Response surface methodology was used for the optimization of bovine serum albumin (BSA) flux and rejection. The results of the morphological as well as permeation studies depicted that permeate flux and antifouling nature were increased with the amount of AMPS present in the membrane matrix. The antifouling study of the prepared membranes was undertaken by using BSA solution of 1000 mg/L. Positive results were seen with the increase in amount of AMPS, since, the total membrane resistance has been decreased from 0.95 (MR0) to 0.74 (MR4). Separation of humic acid from aqueous medium was also performed with the best performing membrane (MR4, having the highest amount of AMPS). Separation efficiency of 100% and 94% were obtained using 10 mg/L and 50 mg/L of HA, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 45290.