Design of a Six-link Mechanism for a Micro Air Vehicle

Micro air vehicle (MAV) is a small flight vehicle that uses lift-generating mechanism different from the mechanism used for a larger aircraft. The MAV may require configurations that are more unusual and approaches, ranging from low aspect ratio fixed wings to rotary wings, or even flapping wings. One of the most efficient lift-generating mechanism in small geometries is observed in the one species of insects Encarsia formosa, as reported by Weis Fogh. This is achieved by generating lift prior to setting up of net circulation. In this paper, the design of a flapping mechanism used to realise the Weis Fogh mechanism of lift generation is described. A single-drive design using concepts of motion synthesis by kinematic inversion technique, followed by dynamic analysis, is presented. This simplification opens the way for future miniaturisation of these devices at economic costs

Development of Advanced Hybrid, Nano-Sized, Brine Sludge Impregnated MWCNT Composite Material Useful for Broad Application Spectrum

A novel microwave irradiated process has been developed for the synthesis of advanced hybrid, nano-sized, functionalized, brine sludge impregnated MWCNT composite material useful for broad application spectrum. MWCNTs and brine sludge are mainly used as raw materials and are heated in flask using microwave synthesizer in the temperature range of 50-60 ºC for the duration of 20- 25 minutes. Brine sludge act as a novel agent wherein simultaneously and synergistically in-situ funtionization of MWCNTs takes place and therefore enabling synthesis of dark grey colored advanced hybrid, nano-sized, functionalized, brine sludge impregnated MWCNT composite material useful for broad application spectrum. The synthesized advance material has been characterized by various complementary techniques namely XRD, FTIR, FESEM and EDXA. FESEM study reveals the increase in the thickness of the MWCNT wall thereby confirms the brine sludge impregnation on MWCNT. The applications of synthesized material lie in the area such as radiation shielding materials, hybrid polymeric materials to advanced chemically designed composite (ACDC) materials useful for broad application spectrum

Scale Inside-Out: Rapid Mitigation of Cloud DDoS Attacks

The distributed denial of service (DDoS) attacks in cloud computing requires quick absorption of attack data. DDoS attack mitigation is usually achieved by dynamically scaling the cloud resources so as to quickly identify the onslaught features to combat the attack. The resource scaling comes with an additional cost which may prove to be a huge disruptive cost in the cases of longer, sophisticated, and repetitive attacks. In this work, we address an important problem, whether the resource scaling during attack, always result in rapid DDoS mitigation? For this purpose, we conduct real-time DDoS attack experiments to study the attack absorption and attack mitigation for various target services in the presence of dynamic cloud resource scaling. We found that the activities such as attack absorption which provide timely attack data input to attack analytics, are adversely compromised by the heavy resource usage generated by the attack. We show that the operating system level local resource contention, if reduced during attacks, can expedite the overall attack mitigation. The attack mitigation would otherwise not be completed by the dynamic scaling of resources alone. We conceived a novel relation which terms “Resource Utilization Factor” for each incoming request as the major component in forming the resource contention. To overcome these issues, we propose a new “Scale Inside-out” approach which during attacks, reduces the “Resource Utilization Factor” to a minimal value for quick absorption of the attack. The proposed approach sacrifices victim service resources and provides those resources to mitigation service in addition to other co-located services to ensure resource availability during the attack. Experimental evaluation shows up to 95 percent reduction in total attack downtime of the victim service in addition to considerable improvement in attack detection time, service reporting time, and downtime of co-located services

DDoS victim service containment to minimize the internal collateral damages in cloud computing

Recent Distributed Denial of Service (DDoS) attacks on cloud services demonstrate new attack effects, including collateral and economic losses. In this work, we show that DDoS mitigation methods may not provide the expected timely mitigation due to the heavy resource outage created by the attacks. We observe an important Operating System (OS) level internal collateral damage, in which the other critical services are also affected. We formulate the DDoS mitigation problem as an OS level resource management problem. We argue that providing extra resources to the victim's server is only helpful if we can ensure the availability of other services. To achieve these goals, we propose a novel resource containment approach to enforce the victim's resource limits. Our real-time experimental evaluations show that the proposed approach results in reduction in the attack reporting time and victim service downtime by providing isolated and timely resources to ensure availability of other critical services

Investigations of Gold-Graphene Nanocomposite for ORR in Aqueous Electrolytes

Oxygen reduction reaction (ORR) is an essential reaction step in fuel cell and metal-air batteries. The kinetics of ORR is very sluggish; it requires very high potential to occur. Many interesting articles have been published to enhance the kinetics. In this direction, we are working on metal nanoparticles modified graphene sheet. Gold nanoparticles are attached on two dimensional graphene sheets by in-situ reduction of metal ion in an aqueous reaction mixture. The synthesized nanocomposite is characterized by powder XRD, XPS and Raman spectroscopy. Microscopy image shows gold nanoparticles are attached to graphene sheets. ORR is studied in 0.1 M KOH and 0.1 M K2SO4 electrolytes. O2 reduction in aqueous electrolytes produces water molecules on gold-graphene nanocomposite

Association of Intronic Single Nucleotide Polymorphism (SNP) of CALM 1 gene with Osteoarthritis of the Knee in Indian Population: A Case-control Study

Osteoarthritis knee is one of the most prevalent disorders in the Indian subcontinent. The wide prevalence and varying features makes it a disease of disguise. Multiple etiological factors have been described. The most recent is genetic contribution in the causation of the disease. This case control study was conducted in the Department of Orthopaedic Surgery, CSM Medical University, Lucknow in collaboration with IIT, Kanpur. 120 cases and 120 controls were enrolled. Clinico-radiological features were noted and symptomatic clinical scoring was done. Genetic polymorphism in relation to intronic region of CALM 1 gene was studied by DNA extraction, Polymerase chain reaction (PCR) and Restriction fragment length polymorphism (RFLP) method. Statistical analysis was done using Stata software. There was no significant difference between age, sex and BMI among cases and controls (p value > .05). ESR (p value =0.0000), fasting blood sugar (p value= 0.0004) and serum uric acid (p value=0.0001) were significantly different among cases and controls. SNP was found in significantly higher number in cases than controls (p value = .0022). Heterozygosity was found only in 5 cases. Logistic regression has also proved significant association of occurrence of Single Nucleotide Polymorphism (SNP) with disease. CALM-1 gene intronic SNP (rs3213718) is present in Indian population. Occurrence of this SNP is significantly affecting the disease

First measurement of the Head-Tail directional nuclear recoil signature at energies relevant to WIMP dark matter searches

We present first evidence for the so-called Head-Tail asymmetry signature of neutron-induced nuclear recoil tracks at energies down to 1.5 keV/amu using the 1m^3 DRIFT-IIc dark matter detector. This regime is appropriate for recoils induced by Weakly Interacting Massive Particle (WIMPs) but one where the differential ionization is poorly understood. We show that the distribution of recoil energies and directions induced here by Cf-252 neutrons matches well that expected from massive WIMPs. The results open a powerful new means of searching for a galactic signature from WIMPs.Comment: 4 pages, 6 figures, 1 tabl

Low Energy Electron and Nuclear Recoil Thresholds in the DRIFT-II Negative Ion TPC for Dark Matter Searches

Understanding the ability to measure and discriminate particle events at the lowest possible energy is an essential requirement in developing new experiments to search for weakly interacting massive particle (WIMP) dark matter. In this paper we detail an assessment of the potential sensitivity below 10 keV in the 1 m^3 DRIFT-II directionally sensitive, low pressure, negative ion time projection chamber (NITPC), based on event-by-event track reconstruction and calorimetry in the multiwire proportional chamber (MWPC) readout. By application of a digital smoothing polynomial it is shown that the detector is sensitive to sulfur and carbon recoils down to 2.9 and 1.9 keV respectively, and 1.2 keV for electron induced events. The energy sensitivity is demonstrated through the 5.9 keV gamma spectrum of 55Fe, where the energy resolution is sufficient to identify the escape peak. The effect a lower energy sensitivity on the WIMP exclusion limit is demonstrated. In addition to recoil direction reconstruction for WIMP searches this sensitivity suggests new prospects for applications also in KK axion searches

Discovery of Two New Faint Cataclysmic Variables

We report on the discovery of two new faint cataclysmic variables. The objects were selected as candidates from two different imaging surveys aimed at the discovery of such faint systems. One survey used color and variability while the other used color and H$_\alpha$ emission as selection criteria. We present our spectra of the two new variables and discuss their properties. A discussion of the implication of these discoveries on the space density of faint cataclysmic variables is presented.Comment: 4 pages, 4 figures. Accepted to A&A letter