The late-time development of the Richtmyer–Meshkov instability

Measurements have been made of the growth by the Richtmyer–Meshkov instability of nominally single-scale perturbations on an air/sulfur hexafluoride (SF6) interface in a large shock tube. An approximately sinusoidal shape is given to the interface by a wire mesh which supports a polymeric membrane separating the air from the SF6. A single shock wave incident on the interface induces motion by the baroclinic mechanism of vorticity generation. The visual thickness delta of the interface is measured from schlieren photographs obtained singly in each run and in high-speed motion pictures. Data are presented for delta at times considerably larger than previously reported, and they are tested for self-similarity including independence of initial conditions. Four different initial amplitude/wavelength combinations at one incident shock strength are used to determine the scaling of the data. It is found that the growth rate decreases rapidly with time, ddelta/dt[proportional]t–p (i.e., delta[proportional]t1–p), where 0.67<~p<~0.74 and that a small dependence on the initial wavelength lambda0 persists to large time. The larger value of the power law exponent agrees with the result of the late-time-decay similarity law of Huang and Leonard [Phys. Fluids 6, 3765–3775 (1994)]. The influence of the wire mesh and membrane on the mixing process is assessed

Isolation and identification of bacteria causing arthritis in chickens

Sixty chickens 30-55 days old with arthritis symptoms, were collected from different broiler chickens farms, all samples were examined clinically, post mortem and bacterial isolation were done. The results revealed isolation of 26 (50.98%) of Staphylococcus aureus, which were found highly sensitive to amoxycillin. The experimental infection of 10 chickens was carried out on 35 days old by intravenous inoculated with 107 cfu/ml of isolated Staphylococcus aureus. Arthritis occurred in 8 (80%) chickens. Clinical signs and post mortem findings confined to depression, swollen joints, inability to stand

M-GEAR: Gateway-Based Energy-Aware Multi-Hop Routing Protocol for WSNs

In this research work, we advise gateway based energy-efficient routing protocol (M-GEAR) for Wireless Sensor Networks (WSNs). We divide the sensor nodes into four logical regions on the basis of their location in the sensing field. We install Base Station (BS) out of the sensing area and a gateway node at the centre of the sensing area. If the distance of a sensor node from BS or gateway is less than predefined distance threshold, the node uses direct communication. We divide the rest of nodes into two equal regions whose distance is beyond the threshold distance. We select cluster heads (CHs)in each region which are independent of the other region. These CHs are selected on the basis of a probability. We compare performance of our protocol with LEACH (Low Energy Adaptive Clustering Hierarchy). Performance analysis and compared statistic results show that our proposed protocol perform well in terms of energy consumption and network lifetime.Comment: IEEE 8th International Conference on Broadband and Wireless Computing, Communication and Applications (BWCCA'13), Compiegne, Franc

Containment of fast scanning computer network worms

This paper presents a mechanism for detecting and containing fast scanning computer network worms. The countermeasure mechanism, termed NEDAC, uses a behavioural detection technique that observes the absence of DNS resolution in newly initiated outgoing connections. Upon detection of abnormal behaviour by a host, based on the absence of DNS resolution, the detection system then invokes a data link containment system to block traffic from the host. The concept has been demonstrated using a developed prototype and tested in a virtualised network environment. An empirical analysis of network worm propagation has been conducted based on the characteristics of reported contemporary vulnerabilities to test the capabilities of the countermeasure mechanism. The results show that the developed mechanism is sensitive in detecting and blocking fast scanning worm infection at an early stage

Effect of Packet Inter-arrival Time on the Energy Consumption of Beacon Enabled MAC Protocol for Body Area Networks

AbstractOne of the major concerns for the development of Wireless Body Area Network (WBAN) is to increase the network lifetime. IEEE 802.15.4 standard for Medium Access Control (MAC) layer can be used for energy efficient and reliable transmission by modifying the different control parameters. Such a modification is very difficult, because an accurate model for the influence of these control parameters of minimum energy and delay is not available. Moreover, there is no mechanism available how to adopt and implement these parameters that can implement on the Body Nodes (BNs). In this paper, we provide the mechanism for emergency data along with normal and periodic data by modifying the superframe structure. Coordinator transmits and extra beacon upon the request of emergency data. A comprehensive analysis of energy consumption of BNs including the affect of packet inter-arrival time is given in this paper. Analysis show that, Contention Access Period (CAP) of superframe is not feasible for emergency data due to its extra delay and energy

Residents’ Satisfaction with Public Facilities and Neighbourhood Environment in Slum Residential Areas of Jos, Plateau State, Nigeria.

The high density residential areas of Jos were scaled on the basis of level of environmental decay and general planning in order to select the worst residential slum areas for study. Three areas, Gangare, Angwanrogo and Dadinkowa emerged as study sample. The areas were subjected to assessment using questionnaires with a view to determining the residents’ degree of satisfaction with seven loaded factors: public institutions, public facilities, environmental conditions, transportation facilities, recreational facilities, neighbourhood safety and commercial facilities. Results obtained showed a general trend of dissatisfaction of the residents of the areas with all the seven measured factors. The tested hypothesis indicated calculated x2 value of 13.57 which is greater than the theoretical value, 2.73 at α 0.05 and 1.65 at α 0.01 which implied that there is a significant level of correlation in the degree of satisfaction among the three residential areas. Therefore, the researchers concluded that similar policies and programmes aimed at improving the environmental setting and public facilities will be suitable for all slum residential areas of Jos. Following this, it is recommended among others that, the areas should be declared   as Action Plan Areas (APA) for emergency action with priority accorded to provision of access roads, drainages, planned refuse disposal systems, and public enlightenment programmes on the benefits of environmental sanitation. Public Private Partnership (PPP), State and local government authorities are recommended for the implementation process. For sustainability of the programmes and projects, the involvement of members of the communities is also recommended. Keywords: Residents’ satisfaction, public facilities, high density, residential areas, loaded factor

Trajectories Describing the Evolution of Polarized Light in Homogeneous Anisotropic Media and Liquid Crystals

Trajectories are given that describe the evolution of the ellipse of polarization in the complex plane for light propagating in a homogeneous anisotropic medium and along the helical axis of a cholesteric liquid crystal. For the general homogeneous anisotropic medium that exhibits combined birefringence and dichroism the trajectory is a spiral that converges to the low-absorption eigenpolarization. For pure birefringence the trajectory becomes a complete circle that encloses one eigenpolarization, whereas for pure dichroism the trajectory becomes an arc of a circle that ends at the low-absorption eigenstate. The case of a cholesteric (or twisted nematic) liquid crystal leads to an interesting family of trajectories that can be considered as distorted hypo- or epicycloids. These trajectories are nonrepetitive (open) and may show multilobes or branches depending upon the initial polarization and the properties of the liquid crystal. Graphs are also presented where the ellipticity and azimuth are plotted separately as functions of distance along the helical axis

Trajectories Describing the Evolution of Polarized Light in Homogeneous Anisotropic Media and Liquid Crystals

Trajectories are given that describe the evolution of the ellipse of polarization in the complex plane for light propagating in a homogeneous anisotropic medium and along the helical axis of a cholesteric liquid crystal. For the general homogeneous anisotropic medium that exhibits combined birefringence and dichroism the trajectory is a spiral that converges to the low-absorption eigenpolarization. For pure birefringence the trajectory becomes a complete circle that encloses one eigenpolarization, whereas for pure dichroism the trajectory becomes an arc of a circle that ends at the low-absorption eigenstate. The case of a cholesteric (or twisted nematic) liquid crystal leads to an interesting family of trajectories that can be considered as distorted hypo- or epicycloids. These trajectories are nonrepetitive (open) and may show multilobes or branches depending upon the initial polarization and the properties of the liquid crystal. Graphs are also presented where the ellipticity and azimuth are plotted separately as functions of distance along the helical axis

Synthesis of Zeolite Y from Kaolin Using Novel Method of Dealumination

In this study Zeolite Y was successfully synthesized from local kaolin in Ado-0do Ota, Ogun state Nigeria through a novel process of dealumination. The thermal activation of kaolin was achieved through the process of metakaolinization at 850 oC for 6 hours in a furnace and dealumination with H2SO4 in order to achieve a desire silica/alumina molar ratio between 3 and 8. Zeolitization involved alkaline attack of dealuminated metakaolin and its consequent transformation into Zeolite Y crystal. Silica/Alumina molar ratio of 5.84 of metakaolin was synthesized under hydrothermal treatment with aqueous NaOH at atmospheric pressure. It was then aged for 7 days at room temperature and crystallized at 100 oC for 24 hours; Zeolite NaY of molar ratio of 3.46 was achieved and then modified to its hydrogen form by ion exchange with NH4Cl. The molar ratio of Zeolite Y in hydrogen form is 3.22. The samples were characterized with X-ray Fluorescence (XRF), X-Ray Diffraction (XRD), and Scanning Electron Microscope (SEM). The result showed that zeolite Y was synthesized from Arobieye mined kaolin with a molar ratio of 6SiO2 : Al2O3 : 9Na2O : 24H2O by ageing at room temperature for 24 hours and crystallized at 100 oC for 24 hours