A flexible UV nanosensor based on reduced graphene oxide decorated ZnO nanostructures

A low-cost, compatible with flexible electronics, high performance UV sensor has been achieved from a reduced graphene oxide (RGO) decorated hydrangea-like ZnO film on a PDMS substrate. The hydrangea-like ZnO UV sensor has the best UV sensing performance among devices made of three kinds of ZnO nanostructures synthesized by a hydrothermal method, and demonstrated a dramatic enhancement in on/off ratio and photoresponse current by introducing an appropriate weight ratio of RGO. The on/off ratio of the 0.05% RGO/ZnO sensor increases almost one order of magnitude compared to that of a pristine hydrangea-like ZnO UV sensor. While for the 5% RGO decorated ZnO sensor, the photoresponse current reaches as high as ～1 μA and exceeds 700 times that of a ZnO UV sensor. These results indicate that RGO is an appropriate material to enhance the performance of ZnO nanostructure UV sensors based on its unique features, especially the high optical transparency and excellent electronic conductivity. Our findings will make RGO/ZnO nanohybrids extraordinarily promising in optoelectronics, flexible electronics and sensor applications.     

Preparation of grass-like GaN nanostructures: Its PL and excellent field emission properties

We here report highly pure and single crystalline grass-like gallium nitride (GaN) nanostructures obtained on silicon substrate via catalyst-assisted CVD route under NH₃ atmosphere inside horizontal tube furnace (HTF) by pre-treating the precursors with aqueous NH₃. The as-obtained GaN nanostructures were characterized by XRD, SEM, EDS, HRTEM and SAED. The field emission (FE) characteristics of grass-like GaN nanostructures exhibited a turn-on field of 7.82 V μm^− 1 and a threshold field of 8.96 V μm^− 1 which are quite reasonable for applications in electron emission devices, field emission displays and vacuum microelectronic devices. Room temperature photoluminescence (PL) measurements of grass-like GaN nanostructures exhibited a strong near-band-edge emission at 368.8 nm (3.36 eV) without any defects related emissions which shows its potential applications in optoelectronics.     

Tungsten Oxide@Polypyrrole Core–Shell Nanowire Arrays as Novel Negative Electrodes for Asymmetric Supercapacitors

Among active pseudocapacitive materials, polypyrrole (PPy) is a promising electrode material in electrochemical capacitors. PPy‐based materials research has thus far focused on its electrochemical performance as a positive electrode rather than as a negative electrode for asymmetric supercapacitors (ASCs). Here high‐performance electrochemical supercapacitors are designed with tungsten oxide@PPy (WO₃@PPy) core–shell nanowire arrays and Co(OH)₂ nanowires grown on carbon fibers. The WO₃@PPy core–shell nanowire electrode exhibits a high capacitance (253 mF/cm²) in negative potentials (–1.0–0.0 V). The ASCs packaged with CF‐Co(OH)₂ as a positive electrode and CF‐WO₃@PPy as a negative electrode display a high volumetric capacitance up to 2.865 F/cm³ based on volume of the device, an energy density of 1.02 mWh/cm³, and very good stability performance. These findings promote the application of PPy‐based nanostructures as advanced negative electrodes for ASCs.     

Congestion‐Aware Handover in LTE Systems for Load Balancing in Transport Network

Long‐Term Evolution employs a hard handover procedure. To reduce the interruption of data flow, downlink data is forwarded from the serving eNodeB (eNB) to the target eNB during handover. In cellular networks, unbalanced loads may lead to congestion in both the radio network and the backhaul network, resulting in bad end‐to‐end performance as well as causing unfairness among the users sharing the bottleneck link. This work focuses on congestion in the transport network. Handovers toward less loaded cells can help redistribute the load of the bottleneck link; such a mechanism is known as load balancing. The results show that the introduction of such a handover mechanism into the simulation environment positively influences the system performance. This is because terminals spend more time in the cell; hence, a better reception is offered. The utilization of load balancing can be used to further improve the performance of cellular systems that are experiencing congestion on a bottleneck link due to an uneven load.     

Keyless Security in Wireless Networks

Security and privacy issues in RFID technology gain tremendous popularity recently. However, existing work on RFID authentication problems always make assumptions such as (1) hash function can be fully employed in designing RFID protocols; (2) channels between readers and server are always secure. The first assumption is not suitable for EPC Class-1 Gen-2 tags, which has been challenged in many research work, while the second one cannot be directly adopted in mobile RFID applications where wireless channels between readers and server are always insecure. To solve these problems, in this paper, we propose a novel ultralightweight and privacy-preserving authentication protocol for mobile RFID systems. We only use bitwise XOR, and several special constructed pseudo-random number generators to achieve our aims in the insecure mobile RFID environment. We use GNY logic to prove the security correctness of our proposed protocol. The security and privacy analysis show that our protocol can provide several privacy properties and avoid suffering from a number of attacks, including tag anonymity, tag location privacy, reader privacy, forward secrecy, and mutual authentication, replay attack, desynchronization attack etc. We implement our protocol and compare several parameters with existing work, the evaluation results indicate us that our protocol significantly improves the system performance.     

Performance comparison of JPEG,JPEG 2000, and newly developed CSI‐JPEG by adopting different color models

The major issues of using less storage space and wanting higher transmission rates for information in the form of high quality color images was taken into consideration. Two experiments were conducted in order to investigate and compare performance of compression standard including JPEG 1992 and JPEG 2000, and a newly developed CSI‐JPEG. The CSI‐JPEG is an amalgamation of Cubic Spline Interpolation (CSI) with baseline JPEG 1992 algorithm. The performance of different image compression algorithms was evaluated using different color models/spaces in terms of compression rate, color accuracy, and visual quality. The results from three assessment methods consistently showed that JPEG 2000 and CSI‐JPEG performed significantly better compared with JPEG 1992 for small color differences (in the range of acceptability). Moreover, the CAM02‐UCS performed best among other selected models in terms of compression rate and image performance for all three image compression algorithms. The results from the visual assessment also confirmed this. It was also found that CIEDE2000 can be reliably used for assessing quality of compressed images with low levels of distortion. © 2016 Wiley Periodicals, Inc. Col Res Appl, 42, 460–473, 2017     

Intracerebral hemorrhage in blacks. Risk factors, subtypes, and outcome

BACKGROUND AND PURPOSE: Blacks are at a higher risk for intracerebral hemorrhage (ICH) than whites; however, few data are available regarding the demographic and clinical characteristics of ICH among blacks. METHODS: We determined the frequency of risk factors, etiologic subtypes, and outcome among consecutive black patients admitted with nontraumatic ICH to a university-affiliated public hospital. RESULTS: The most common risk factors in the 403 black patients with ICH were preexisting hypertension (77%), alcohol use (40%), and smoking (30%). Among the 91 nonhypertensive patients, 21 (23%) were diagnosed with hypertension after onset. Compared with women, men had a younger age of onset (54 versus 60 years; P < .001) and higher frequency of alcohol use (54% versus 22%; P < .001) and smoking (39% versus 17%; P < .001). ICH secondary to hypertension (n = 311) and of undetermined etiology (n = 73) were the most common subtypes in blacks. Patients aged 65 years and older (compared with those aged 15 to 44 years; P = .001) and women (compared with men; P = .02) were more likely to be dependent at discharge. CONCLUSIONS: Primary preventive strategies are required to reduce the high frequency of modifiable risk factors predisposing to ICH in blacks.     

Locality-aware process placement for parallel and distributed simulation in cloud data centers

The Journal of Supercomputing - Cloud is a multi-tenant paradigm providing resources as a service. With its easily available computing infrastructure, researchers are adopting cloud for...     

Simulation and Energy Management in Smart Environment Using Ensemble of GA and PSO

Wireless Personal Communications - Smart, intelligent and sustainable power consumption model in residential sector received attraction of the researchers in last couple of years. Numerous...