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A domain‐adaptive technique which maps the unknown, time‐dependent, curvilinear geometry of annular liquid jets into a unit square is used to determine the steady state mass absorption rate and the collapse of annular liquid jets as functions of the Froude, Peclet and Weber numbers, nozzle exit angle, initial pressure and temperature of the gas enclosed by the liquid, gas concentration at the nozzle exit, ratio of solubilities at the inner and outer interfaces of the annular jet, pressure of the gas surrounding the liquid, and annular jet's thickness‐to‐radius ratio at the nozzle exit. The domain‐adaptive technique yields a system of non‐linearly coupled integrodifferential equations for the fluid dynamics of and the gas concentration in the annular jet, and an ordinary differential equation for the time‐dependent convergence length. An iterative, block‐bidiagonal technique is used to solve the fluid dynamics equations, while the gas concentration equation is solved by means of a line Gauss‐Seidel method. It is shown that the jet's collapse rate increases as the Weber number, nozzle exit angle, temperature of the gas enclosed by the annular jet, and pressure of the gas surrounding the jet are increased, but decreases as the Froude and Peclet numbers and annular jet's thickness‐to‐radius ratio at the nozzle exit are increased. It is also shown that, if the product of the inner‐to‐outer surface solubility ratio and the initial pressure ratio is smaller than one, mass is absorbed at the outer surface of the annular jet, and the mass and volume of the gas enclosed by the jet increase with time.

The purpose of this paper is to quantify the relative importance of the multiphase model for the simulation of a gas bubble impacted by a normal shock wave in water. Both the free-field case and the collapse near a wall are investigated. Simulations are performed on both two- and three-dimensional configurations. The main phenomena involved in the bubble collapse are illustrated. A focus on the maximum pressure reached during the collapse is proposed.

Simulations are performed using an inviscid compressible homogeneous solver based on different systems of equations. It consists in solving different mixture or phasic conservation laws and a transport-equation for the gas volume fraction. Three-dimensional configurations are considered for which an efficient massively parallel strategy was developed. The code is based on a finite volume discretization for which numerical fluxes are computed with a Harten, Lax, Van Leer, Contact (HLLC) scheme.

The comparison of three multiphase models is proposed. It is shown that a simple four-equation model is well-suited to simulate such strong shock-bubble interaction. The three-dimensional collapse near a wall is investigated. It is shown that the intensity of pressure peaks on the wall is drastically increased (more than 200 per cent) in comparison with the cylindrical case.

The study of bubble collapse is a key point to understand the physical mechanism involved in cavitation erosion. The bubble collapse close to the wall has been addressed as the fundamental mechanism producing damage. Its general behavior is characterized by the formation of a water jet that penetrates through the bubble and the generation of a blast wave during the induced collapse. Both the jet and the blast wave are possible damaging mechanisms. However, the high-speed dynamics, the small spatio-temporal scales and the complicated physics involved in these processes make any theoretical and experimental approach a challenge.

Cavitation erosion is a major problem for hydraulic and marine applications. It is a limiting point for the conception and design of such components.

Such a comparison of multiphase models in the case of a strong shock-induced bubble collapse is clearly original. Usually models are tested separately leading to a large dispersion of results. Moreover, simulations of a three-dimensional bubble collapse are scarce in the literature using such fine grids.

This paper analyses numerically the effects of sinusoidal g—jitter on the fluid dynamics of, and mass transfer in, annular liquid jets. It is shown that the pressure and volume of the gases enclosed by the jet, the gas concentration at the jet’s inner interface, and the mass absorption rates at the jet’s inner and outer interfaces are sinusoidal functions of time which have the same frequency as that of the g—jitter. The amplitude of these oscillations increases and decreases, respectively, as the amplitude and frequency, respectively, of the g—jitter is increased. The pressure coefficient and the gas concentration at the jet’s inner interface are in phase with the applied g—jitter and the amplitude of their oscillations increases almost linearly with the amplitude of the g—jitter. The mass absorption rates at the jet’s inner and outer interfaces exhibit a phase lag with respect to the g—jitter.

The purpose of this paper is to investigate the applicability of the smoothed particle hydrodynamics (SPH) method in the jet formation process of a cylindrical-shaped charge (CSC). Different SPH formulations, suggested in other works, to other applications, are brought together in order to build a model that represents the phenomenon of detonation of a CSC in a more realistic way.

A two-dimensional (2D) SPH formulation using cylindrical coordinates is adopted to simulate CSCs. The problem of fluid-solid interaction between the detonation wave of the explosive and the metal liner, numerically unstable due to the great difference in density between the phases, is resolved adopting the multi-phase strategy. A new proposition of artificial viscosity is incorporated in order to account the convergence effect of the liner particles toward the axis of symmetry of the charge. Two numerical examples are used to validate the formulation. In the first, the velocity and length differences between the jets formed from a CSC and a linear-shaped charge (LSC) using planar detonation on both are compared. In the second example, the effect of the conical cavity angle in the maximum jet velocity is evaluated, comparing the simulated results of CSC with four different cavity angles, with the experimental results.

The results show that the 2D SPH method in cylindrical coordinates is able to simulate the detonation process of a CSC. Accordingly with the formulations used, the following conclusions can be made: the multi-phase strategy is able to capture the multi-material interface of the fluid-solid interaction between the detonation wave and the metal liner; and in the cylindrical geometry, a second artificial viscosity is necessary in order to include the convergence effect of the particles toward the axis of symmetry and obtaining more realistic results for the jet velocity.

The applicability of the SPH method to simulate LSCs has been tested and verified in other works, but there are not references that address the application of the SPH method to simulate CSCs. CSCs are widely used in the defense industry and in the oil industries. In the oil industry, the perforating process may currently be the most common use of such a device. For this reason, it is believed that the proposed formulation in this paper is a good alternative to these specific applications.

The competitive environment of the Indian aviation industry is studied using Porter's five forces model. The SWOT analysis is used to examine the competitive position of Jet Airways. The role of Merger & Acquisition in the current Jet Airways crisis is also examined. Relevant texts studied are as follows: Kazmi, A. and Kazmi A. (1992). Strategic Management. McGraw-Hill Education; and Porter, M. (2008). The Five Competitive Forces That Shape Strategy. Harvard business review. 86. 78–93, 137.

This data for this case was extracted from secondary sources. These sources comprise newspaper articles, reports from the industry, reports of the company and the company's website. For gaining clarity over concepts, strategic management book by Azhar Kazmi and Adela Kazmi was referred. This case also uses websites such as moneycontrol.com to analyze financial health of the company. In the end, this case also uses some existing reports from the sources like World Bank and plane spotters to analyze the status of Jet Airways and also Indian aviation industry. This case has been tested in the classroom with MBA students in a class of Business Policy and Strategic management.

The Jet Airways, which once had the largest market share in the Indian aviation industry, has reached bankruptcy. Mr. Naresh Goyal, known for his aggressive expansion strategies, has already filed for bankruptcy. This case presents how buying aircrafts' obsession with poor choices on Mergers/Acquisitions could result in bankruptcy. The same could be substantiated from the fact that Goyal had many (197) of his fleet's latest aircraft. Goyal was also criticized for buying Sahara Airlines, which was performing poorly in the market. Spending a large portion of the budget in capital expenditure in an industry where operational cost is very high, only the cost of turbine fuel amounts to 50% of total operational expense. The high expenditure on capital budget and increasing operational cost weaken the financial position of Jet Airways. Despite earning decent revenue and having the highest market share in 2010, Jet Airways made losses in three consecutive years, i.e. from 2009 to 2011. After 2011, when the Indian aviation industry witnessed a high level of competition and growth in low-cost carriers (LCC), Jet Airways' survival was up for a toss. Despite the desperate measures of cost-cutting and attracting potential investors, Jet Airways reached the verge of bankruptcy. The current case emphasized the need to balance safe and riskier options, even for the market leaders like Jet Airways could fail due to poor strategic choices. This case presents some harsh realities on funds allocation. In 2010, where Jet Airways secure the highest market share and decent total revenue, it realized net losses. The case study also explains the need to adapt to the dynamics of the industry. After 2011, when LCC started dominating the Indian aviation industry, Jet Airways did not change its operation strategy and facing severe consequences. The case was about the poor strategic decisions taken by the founder of Jet Airways, Mr. Naresh Goyal, which adversely affected the health of the airline. The case also explores the possible strategic choices that Goyal could have taken to ensure Jet Airways' survival. Through this case, an attempt had been made to highlight the importance of various concepts that we need to understand while making a strategic decision for any organization. In the end, this case emphasized the role of strategy in managing an organization successfully.

The case study's target group should be Undergraduate and Postgraduate students of the Management discipline who study Strategic Management as a specialization or as the subject. This case can also be used in the Management Development Program for senior executives taking any vocational course or workshop on Business Strategy. The case focuses on one of the fastest emerging markets, i.e. India, and could be proven valuable for many multinationals companies. The case presents the changing competitive dynamics of the Indian aviation industry. The central theme on which the case revolves is the importance of sound strategic choices in a dynamic market or industry. After analyzing the case, the students would understand the complex nature of strategic decision-making and any poor strategic decisions ripple effect. This case could teach essential strategic management concepts like "SWOT analysis" and "PESTEL analysis." This case should be used to teach strategic management concepts only and not act as a judgment tool for any organization.

The purpose of the paper is the elucidation of certain mechanisms of laser material processing in general and laser micro sintering in particular. One major intention is to emphasize the synergism of the various effects of q‐switched laser pulses upon metal and ceramic powder material and to point out the non‐equilibrium character of reaction steps.

Recent results and observations, obtained in development of “laser micro sintering,” are surveyed and analyzed. By breaking down the overall process into relevant steps and considering their possible kinetics, an approach is made towards interpreting specific phenomena of laser micro sintering. Thermodynamics upon heating of the material as well as its photo‐electronic response to the incident radiation are considered.

The findings corroborate a model whereby short pulses of high intensity provide non‐equilibrium pressure conditions at the location of incidence, that allow for the melting of metal powder with an almost immediate expansion of a plasma and/or vapor bulb. Thereby the molten material is condensed and propelled towards the substrate. A final boiling eruption after each pulse is the reason for the morphology of the laser micro‐sintered surfaces and can prevent oxidation when the process is conducted under normal atmosphere. In sintering of ceramics, the short pulsed and intensive radiation increases the chance to excite the material even with photon energies below the bandgap value and it lowers the risk of running into a destructive avalanche.

Owing to the stochastic character of the respective sintering event, that is initiated by each individual pulse, the gathered data are not suitable yet for the formulation of an exact quantitative function between sintering behavior and laser parameters.

The qualitative findings yield a good rule of thumb for the choice of parameters in laser sintering on a micrometer scale and the model is conducive for advanced interpretation of other phenomena in laser material processing besides sintering.

The kinetics and thermodynamics of laser sintering with q‐switched pulses are approached by a qualitative explanation. The heterogeneous and non‐equilibrium character of the processes is taken into account; this character is often neglected by researchers in the area.

The resurgence of Austin Rover from the doldrum days of BL is one of the great success stories of British industry in the 1980's. Accompanying the attention to design, mechanical reliability and quality of finish that has made such cars as the Metro, the Maestro, the Montego and the ubiquitous Land Rover all top sellers, has been the great emphasis that is now placed on cleaning in power train operations.

The purpose of this paper is to study major man‐made system disasters and to suggest a solution for filling the noted gaps in control systems interfaces and to render those vital considerations for the next‐generation disaster management control systems.

This research analyzes the nature of large‐scale disasters and observes that most man‐made system disasters are composed of many related events that interact with one another.

The findings show evidence of a common path to catastrophe. These functional failures resulted from the information gaps that eventually contribute to the development of a tragedy. Because of the intricate interconnections among related events of a developed calamity, an integrated approach to man‐made disaster detection and prevention as well as emergency management is required.

Conducting an analysis of the typical contingency control structures, the authors suggest that disaster or emergency managers adopt a pessimistic and quasi‐intelligent orientation to monitor and control critical systems.

This research presents a generic threat‐driven disaster management control system design with advanced model bases and decision support technologies to enhance conventional disaster management control systems and to supplement management responses so that the sphere and magnitude of damage can be minimized.