Highly scalable non-volatile and ultra-low-power phase-change nanowire memory

The search for a universal memory storage device that combines rapid read and write speeds, high storage density and non-volatility is driving the exploration of new materials in nanostructured form. Phase-change materials, which can be reversibly switched between amorphous and crystalline states, are promising in this respect, but top-down processing of these materials into nanostructures often damages their useful properties. Self-assembled nanowire-based phase-change material memory devices offer an attractive solution owing to their sub-lithographic sizes and unique geometry, coupled with the facile etch-free processes with which they can be fabricated. Here, we explore the effects of nanoscaling on the memory-storage capability of self-assembled Ge2Sb2Te5 nanowires, an important phase-change material. Our measurements of write-current amplitude, switching speed, endurance and data retention time in these devices show that such nanowires are promising building blocks for non-volatile scalable memory and may represent the ultimate size limit in exploring current-induced phase transition in nanoscale systems.     

Integration of a Photovoltaic Panel with an Electric City Car

Abstract—Autonomy of light electric vehicles with limited mobility can be improved by assisting onboard energy sources, such as battery and ultra-capacitors, by solar energy. This article discusses the integration of a photovoltaic panel with an electric city car. The Photovoltaic Geographical Information Systems of Joint Research Center, Europe, is used for estimating the solar irradiance. Based on the estimations, a DC-to-DC boost converter topology is considered to interface the panel with the DC bus of the electric car. Experimental evaluation of the performance is carried out under a real climatic situation. An analytical loss model is used to comment on the associated losses and to explain the measured changes in gain and efficiency under varying irradiance. Acceptable extension in the autonomy of the electric city car is predicted from the results.     

Small GTPases and Their Regulators: A Leading Road toward Blood Vessel Development in Zebrafish

Members of the Ras superfamily have been found to perform several functions leading to the development of eukaryotes. These small GTPases are divided into five major subfamilies, and their regulators can “turn on” and “turn off” signals. Recent studies have shown that this superfamily of proteins has various roles in the process of vascular development, such as vasculogenesis and angiogenesis. Here, we discuss the role of these subfamilies in the development of the vascular system in zebrafish.     

A prefix-based approach for joint Doppler and channel estimation in underwater communication

Developing a reliable and robust underwater acoustic communication system is a difficult task due to the complicated nature of the underwater channel, non-stationary noise, and several other factors. Indeed, channel estimation or equalization presents numerous challenges in this non-stationary, highly Doppler, multipath environment; as a result, traditional equalizers and PLL-based methods have limited performance. Generally, communication over such time-varying channels is accomplished via packets that contain a prefix/preamble signal for training, a payload containing the actual data, and a silent period for proper alignment. The prefix signal must be designed properly because it is used to estimate the channel and determine the start of the packet. In this paper, we propose a new prefix signal based on the hyperbolic chirp signal, which has Doppler invariance properties. These properties enable the extraction of the entire packet even under severe multipath and Doppler. Our new proposed prefix signal can accurately and efficiently characterize an underwater channel by estimating the multipath delay, amplitude, and Doppler scales. Our new method has been validated through extensive simulations using various channel models for its robustness and effectiveness under various conditions. It has also been tested on a real-world channel.     

Development of in-situ pico hydropower from treated drain wastewater

Clean Technologies and Environmental Policy - Hydropower contributes around 13% of the total renewable power generation in India. Hydraulic power plants are dependent on diversion...