Prediction of Initial and Striking Velocity of Primary Fragments from Cased Spherical Explosive inside Steel Cubical Structure

Usually, energy generated from an explosive’s detonation is transferred partly in the form of the blast impulse and some in the form of the kinetic energy of casing fragments. When detonation occurs in an explosive casing, it breaks the casing into fragments of different weights with varying velocities. The extent of destruction by these energized fragments depends upon the initial velocity they gain after an explosion. The momentum gained by the fragments decides the capability to perforate a barrier or propagate an explosion. A three-dimensional non-linear FEA method is used to model a box-shaped steel structure. This box-shaped structure is subjected to an internal cased explosion for estimating the initial and striking velocities of primary fragments. The effect of varying charge weight and the effect of the sacrificial wall on the initial and striking velocity of fragments via numerical simulations are also carried out. The initial and striking velocity values obtained through simulation are compared with the design guidelines of the code-based approach, and a good agreement is reported

STU/QCD Correspondence

In this review article we consider a special case of $D=5$, $\mathcal{N}=2$ supergravity called the STU model. We apply the gauge/gravity correspondence to the STU model to gain insight into properties of the quark-gluon plasma. Given that the quark-gluon plasma is in reality described by QCD, therefore we call our study STU/QCD correspondence. First, we investigate the thermodynamics and hydrodynamics of the STU background. Then we use dual picture of the theory, which is type IIB string theory, to obtain the drag force and jet-quenching parameter of an external probe quark.Comment: 56 pages, 20 figures. The paper is review of previous papers arXiv:0905.1466, arXiv:1005.1368, arXiv:1011.2291 and arXiv:1011.2291. Published versio

A global research priority agenda to advance public health responses to fatty liver disease

Background & aims An estimated 38% of adults worldwide have non-alcoholic fatty liver disease (NAFLD). From individual impacts to widespread public health and economic consequences, the implications of this disease are profound. This study aimed to develop an aligned, prioritised fatty liver disease research agenda for the global health community. Methods Nine co-chairs drafted initial research priorities, subsequently reviewed by 40 core authors and debated during a three-day in-person meeting. Following a Delphi methodology, over two rounds, a large panel (R1 n = 344, R2 n = 288) reviewed the priorities, via Qualtrics XM, indicating agreement using a four-point Likert-scale and providing written feedback. The core group revised the draft priorities between rounds. In R2, panellists also ranked the priorities within six domains: epidemiology, models of care, treatment and care, education and awareness, patient and community perspectives, and leadership and public health policy. Results The consensus-built fatty liver disease research agenda encompasses 28 priorities. The mean percentage of ‘agree’ responses increased from 78.3 in R1 to 81.1 in R2. Five priorities received unanimous combined agreement (‘agree’ + ‘somewhat agree’); the remaining 23 priorities had >90% combined agreement. While all but one of the priorities exhibited at least a super-majority of agreement (>66.7% ‘agree’), 13 priorities had 90% combined agreement. Conclusions Adopting this multidisciplinary consensus-built research priorities agenda can deliver a step-change in addressing fatty liver disease, mitigating against its individual and societal harms and proactively altering its natural history through prevention, identification, treatment, and care. This agenda should catalyse the global health community’s efforts to advance and accelerate responses to this widespread and fast-growing public health threat. Impact and implications An estimated 38% of adults and 13% of children and adolescents worldwide have fatty liver disease, making it the most prevalent liver disease in history. Despite substantial scientific progress in the past three decades, the burden continues to grow, with an urgent need to advance understanding of how to prevent, manage, and treat the disease. Through a global consensus process, a multidisciplinary group agreed on 28 research priorities covering a broad range of themes, from disease burden, treatment, and health system responses to awareness and policy. The findings have relevance for clinical and non-clinical researchers as well as funders working on fatty liver disease and non-communicable diseases more broadly, setting out a prioritised, ranked research agenda for turning the tide on this fast-growing public health threat

Investigation into machining performance of microstructurally engineered in-situ particle reinforced magnesium matrix composite

Magnesium and magnesium in-situ composites have significant potential in the application of design and manufacturing for automotive and aerospace industries because of their high specific strength and reduced fuel consumption. But there are many challenges for machining of Mg based alloys and composites because of the high tendency of fire and oxidation. These challenges can be minimized through microstructural engineering. In this present study, the machining performances of AZ91 Mg alloy and in-situ hybrid TiC+TiB2 reinforced AZ91 metal matrix composite was investigated. The effect β-Mg17Al12 phases and grain refinement with and without in-situ particles on machinability were studied through microstructural engineering via aging and friction stir processing. The end milling operation was carried out at different cutting speeds ranging from 25 mm/min to 90 mm/min under dry environment by using an AlTiN-coated tungsten carbide tool. The optimum cutting speed for machining was found to be 75 mm/min based on the surface roughness values of all conditioned materials. The base material with dendritic microstructure was found to have poor machinability in terms of inadequate surface finish and edge-burrs formation. The combined effect of in-situ TiC+TiB2 particles addition and grain refinement enhanced the machining performance of the material with superior surface finish, negligible edge-burr formation and better tool wear resistance. The influence of in-situ TiC+TiB2 particles, β-Mg17Al12 phases and grain refinement on machining characteristics are explained based on the tool wear mechanisms, chip behavior and machining induced affected zone

Age hardening, fracture behavior and mechanical properties of QE22 Mg alloy

The microstructure, mechanical properties and fracture behavior of an as-received QE22 alloy have been investigated under different thermal conditions, including solution treated (ST), under aged (UA), peak aged (PA) and over aged (OA) conditions. A significant increase in hardness of 27%, yield strength of 60% and ultimate tensile strength of 19% was observed in peak aged sample as compared to solution treated sample. The improvements of mechanical strength properties are mainly associated with the metastable λ and β′ precipitates. Grain growth was not observed in the ST samples after subjecting to UA and PA treatments due to the presence of eutectic Mg12Nd particles along the grain boundaries. In over aged sample, significant grain growth occurred because of dissolution of eutectic phase particles. Different natures of crack initiation and propagation were observed under different thermal conditions during tensile testing at room temperature. The mode of failure of solution treated sample is transgranular, cleavage and twin boundary fractures. A mixed mode of transgranular, intergranular, cleavage and twin boundary failure is observed in both peak aged and over aged samples

Investigation into the micro deep drawing capabilities of a specially engineered refined aluminium alloy

During miniaturisation, size of the part comes close to grain size of the material. There is an overall decrease in the total number grains undergoing deformation and most of these are surface grains. Therefore, microscale deformation is marked by abnormal stress-strain response which limits the manufacturing capabilities of microforming. Two distinct phenomena responsible for this are: (i) dominance of single crystal deformation behaviour, and (ii) increased strain localisation due to incompatibly between surface and core grains during deformation. The present work attempts to neutralise these effects by increasing the number of grains in the deformation zone. This has been achieved by engineering refined microstructure in the materials. To develop the refined microstructure, cryorolling followed by controlled annealing treatment has been employed. Microscale deformation behaviour and microforming capabilities of the refined material have been compared with its coarse-grained counterpart by analysing their tensile curves and by post-mortem study of micro deep drawn components over a wide range of sample thicknesses. Material with fully recrystallised, equiaxed, strain-free refined microstructure is found to have the best strain hardening response both in micro and macro deformation domains. This property is also reflected in the micro deep drawing capabilities of the same material

Offline Trajectory Generation for Bipedal Robot Using Linear Inverted Pendulum Model

Reduced order model (ROM)-based controllers have proved to be effective to generate stable bipedal locomotion. However, it is important to understand the limitations and effectiveness of these models without implementing any controllers. This study highlights the versatility of the Linear Inverted Pendulum Model (LIPM) at various walking speeds. Firstly, the Centre of Mass (COM) trajectory has been generated using the LIPM model, and the foot motion trajectory has been created using a sixth-order polynomial function. The trajectory is generated using a predefined step length, speed of locomotion and COM height. Secondly, the task space trajectory has been converted into a joint space trajectory through inverse kinematics for a 6-degree-of-freedom leg. To facilitate the proper walking motion the contact between the foot sole and the ground is implemented. Finally, a simple bipedal robot in MATLAB/Simulink has been modelled and the generated trajectories were implemented

An Efficient Algorithm for Mining Of frequent items using incremental model

Data mining is a part of know ledge Discovery in database process (KDD). As technology advances, floods of data can be produced and shared in many appliances such as wireless Sensor networks or Web click streams. This calls for extracting useful information and knowledge from streams of data. In this paper, We have proposed an efficient algorithm, where, at any time the current frequencies of all frequent item sets can be immediately produced. The current frequency of an item set in a stream is defined as its maximal frequency over all possible windows in the stream from any point in the past until the current state. The experimental result shows the proposed algorithm not only maintains a small summery of information for one item set but also consumes less memory then existing algorithms for mining frequent item sets over recent data streams