Stability derivatives of a oscillating wedges in viscous hypersonic flow

In this paper an oscillating wedge has been considered, and the fluid slabs are kept at 900 to the wedge surface. The solutions of the continuity, momentum,and energy equations are obtained. By using the Rankine-Hugoniot relations for shockwaves, we can find the conditions behind the shock.This theory is unsteady one because of the consideration of effect of secondary wave reflections.Solutions are obtained for hypersonic flow over the wedge by varying different wedge semi vertex angles.These results shows extremely good consistency with Hui's predictions. When the effects of unsteadiness are considered then there is considerable change in the magnitude of the damping derivatives near the leading edge or initial 40 percent of the pivot positions and this difference is only marginal when we further down towards the trailing edge. However, this effect of unsteadiness is not visible in case of the stiffness derivatives. It is observed that the stiffness derivative increases with the increase in the wedge angle due to the increase in the plan form area of the wedge, resulting in the variation in the surface pressure distribution of the wedge. Further, due to the increment in the wedge angle the centre of pressure shifts towards the trailing edge. © Published under licence by IOP Publishing Ltd

An Ethical proposal for a flourishing digitalised financial system

The UK financial services industry is undergoing significant transformative digitalisation through the development of information technology, increased internet communications, computer speed and programming capacity, and application of big data to traditional financial services. In particular, the use of Artificial Intelligence (AI), i.e. intelligence simulated by technological means, and ‘machine learning’, i.e. automatic learning by machines and software based on a computational and statistical process, is becoming increasingly and rapidly prevalent in financial services. The purpose of this thesis is to examine whether, in the light of the potential risks that AI and machine learning will pose upon society, our current ethical, legal and regulatory standards are satisfactory. Primarily, this thesis observes that the separation of ethics as an academic discipline from economic theory and modern finance theory has undermined the efficacy of the ethical, legal and regulatory standards to regulate the financial system. Therefore, it proposes an integrated ethical approach to UK financial regulation, which seeks to regulate the relationship between action, character of the actor, and the consequences of action. The proposed integrated ethical approach is anchored in the ‘social licence for financial markets’, which helps us to focus on the purpose of financial activity to serve the human good, and, ultimately, to improve the well-being of society. This thesis argues that, further to adopting an integrated ethical approach, we should refine our current ethical standards, and introduce new ethical standards. This thesis demonstrates that while an integrated ethical approach may be applied to programme AI and machine learning technology to behave ethically using, overall responsibility for AI and machine learning should remain with humans. In addition, in light of potential responsibility gaps, specially designed liability rules are required. Finally, this thesis will recommend a series of legal and regulatory reforms with the ultimate goal of cultivating a flourishing digitalised financial system

Investigation of base pressure variations in internal and external suddenly expanded flows using CFD analysis

The Aerodynamic base drag because of negative pressure at the backward-facing step is a general obstacle connected with all the moving projectiles. The aerodynamic base drag is undesirable since its contribution to the cumulative drag is substantial. The study of pressure variations in the base region is of immense help for all moving projectiles. The experimental study of aerodynamic drag over missile/ projectile in a wind tunnel has various disadvantages like a considerable amount of air supply is required to conduct the test, the support mechanism is required to hold the model in the wind tunnel test section which creates disturbance in the flow field and introduce the errors in the measurements. In this research paper, the similarities of base pressure variations in internal and external flows are studied using computational fluid dynamics (CFD) analysis. The CFD analysis is carried out at Mach numbers from 0.1 to 3.0. From the results, it has been found that the flow field in the base region of internal and external suddenly expanded flows are nearly the same. The base pressure in external flow can be studied relatively easily by considering it as an internal flow for Mach numbers in the range of 0.1 to 0.4 and 1.4 to 3.0, except when the Mach number is close to unity

Effect of nozzle pressure ratio and control jets location to control base pressure in suddenly expanded flows

In this paper, computational fluid dynamic (CFD) analysis and experiments have been carried out to study the effect of nozzle pressure ratio, i.e. the ratio of inlet pressure to atmospheric pressure, and the pitch circle diameter of the control jets to regulate the base pressure. The variables considered for the analysis as well as the experiments are the nozzle pressure ratio (NPR), the Mach number (M) and the pitch circle diameter (PCD) of the control jets. The area ratio considered for the study is kept constant at 4.84 while the length to diameter (L/D) ratio of an enlarged duct is set constant at 5. The inertia parameter considered for the study is the Mach number. The Mach numbers considered for the study are 1.5, 2.0, and 2.5. The nozzle pressure ratio considered for the study is 2, 5 and 8. Three different pitch circle diameters of control jets considered for the study are 13.1 mm, 16.2 mm and 19.3 mm. From the numerical simulations and the results of the experimental tests, it is found that the control jets are very beneficial to increase the base pressure at higher NPR when the jets issuing from the nozzles are under-expanded. The control jets were able to increase the base pressure value from 160% to 400% at a nozzle pressure ratio 8. It is concluded that the parameter D3 is the most effective pitch circle diameter of the control jets to increase the base pressure

Comparative Study on Two Commercial Strains of Saccharomyces cerevisiae for Optimum Ethanol Production on Industrial Scale

Two commercial strains of Saccharomyces cerevisiae, Saf-Instant (Baker's yeast) and Ethanol red (Mutant) were compared for ethanol production during hot summer season, using molasses diluted up to 6-7° Brix containing 4%-5% sugars. The yeasts were propagated in fermentation vessels to study the effects of yeast cell count and varying concentrations of Urea, DAP, inoculum size and Lactrol (Antibiotic). Continuous circulation of mash was maintained for 24 hours and after this fermenter was allowed to stay for a period of 16 hours to give time for maximum conversion of sugars into ethanol. Saccharomyces cerevisiae strain (Saf-instant) with cell concentration of 400 millions/mL at molasses sugar level of 13%–15% (pH 4.6 ± 0.2, Temp. 32°C ± 1), inoculum size of 25% (v/v), urea concentration, 150 ppm, DAP, 53.4 ppm and Lactrol,150 ppm supported maximum ethanol production (8.8%) with YP/S = 250 L ethanol per tone molasses (96.5% yield), and had significantly lower concentrations of byproducts. By selecting higher ethanol yielding yeast strain and optimizing the fermentation parameters both yield and economics of the fermentation process can be improved

Influence of expansion level on base pressure and reattachment length

In high-speed projectiles like a rocket, the thrust is created by the convergent-divergent nozzle. The flow from the nozzle is exhausted in the enlarged duct of larger diameter to maximize the thrust. When the flow from the nozzle is exhausted in the enlarged duct, the base pressure gets reduced and hence increases base drag. This paper numerically simulates and investigates the flow field and the effectiveness of the Nozzle Pressure Ratio (NPR) on the base pressure, development of the flow field in the enlarged duct, the location of reattachment point, and the reattachment length. The supersonic flow was generated by the C-D nozzle, and the same is exited in the enlarged duct of area ratio 4.84 (ratio of enlarged duct area to nozzle exit area). The base pressure and the wall pressure distribution along the enlarged duct length have been studied. The Mach numbers considered for CFD analysis are 1.5, 2.0 and 2.5. NPR and the L/D ratios of the study are from 2, 5, and 8. Based on the results it is concluded that with enhancement in NPR, the nozzle becomes under-expanded, the reattachment length is reduced and the base pressure tends to get reduced at all the parameters of the present investigation

Enlarge duct length optimization for suddenly expanded flows

In many applications like the aircraft or the rockets/ missiles, the flow from a nozzle needs to be expanded suddenly in an enlarged duct of larger diameter. The enlarged duct is provided after the nozzle to maximize the thrust created by the flow from the nozzle. When the fluid is suddenly expanded in an enlarged duct, the base pressure is generally lower than the atmospheric pressure, which results in base drag. The objective of this research work is to optimize the length to diameter (L/D) ratio of the enlarged duct using the CFD analysis in the flow field from the supersonic nozzle. The flow from the nozzle drained in an enlarged duct, the thrust, and the base pressure are studied. The Mach numbers for the study were 1.5, 2.0, and 2.5. The nozzle pressure ratios (NPR) of the study were 2, 5, and 8. The L/D ratios of the study were 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, and 10. Based on the results, it is concluded that the L/D ratio should be increased to an optimum value to reattach the flow to an enlarged duct and to increase the thrust. The supersonic suddenly expanded flow field is wave dominant, and the results cannot be generalized. The optimized L/D ratios for various combinations of flow and geometrical parameters are given in the conclusion section

Students' Feedback of Written Examination: A Public Sector Medical University Experience

Objective: To determine the students’ perceptions regarding the examination in a public sector medical university. Methodology: This cross-sectional study was conducted at Shaheed Zulfiqar Ali Bhutto Medical University Islamabad. An examination feedback proforma was developed to collect the feedback from students appearing for the written exam for MD/MS/MTA during 2015. Multiple variables were assessed and descriptive analysis was done. Results: The feedback proforma was distributed to 98 candidates with response rate was 68.36%. Overall feedback from students about the examination was positive. Majority of the students were satisfied with the process and arrangements of the examination. However a large number of students did not comment on some important issues. Conclusion: Collecting students’ feedback about examination was a good effort to identify our deficiencies and indication for areas of improvement. This study revealed a positive response from students regarding overall management of the examination process

Comparative study for salt stress among seed, root stock and direct regenerated violet (Viola odorata L.) seedlings in relation to growth, ion contents and enzyme activities

The experiments were carried out to evaluate the comparative study for salt stress among seed, root stock and direct regenerated violet (Viola odorata L.) seedlings. Violet seedlings propagated through tissue culture (direct regeneration) had significantly higher salicylic acid (SA) concentrations from seed and rootstock propagated plants. Random amplified polymorphic DNA (RAPD) studies prior to the salt treatments revealed that genetic similarity at the molecular level among seed, root stock and direct regenerated violet seedlings was 50.9 to 70.5%. NaCl applications (50 mol m–3) reduced plant and root lengths, plant fresh and dry weights in plants obtained through seeds and rootstock as compared to direct regenerated seedlings. Direct regenerated violet showed better plant growth significantly both in saline and non-saline conditions. Seedlings raised through direct regeneration strongly inhibited accumulation of Na+, K+, Ca2+ and Cl− and organic solute accumulations as glycinebetaine (GB) and root total soluble carbohydrates (TSC) but stimulated N and relative water contents (RWC). Direct regenerated seedlings showed an enhanced catalase (CAT), ascorbate peroxidase (APX) and guaiacol dependent peroxidase (GDP) activities as compared to seed and root stock propagated plants. It was concluded that direct regenerated plants had better performance under salt stress in relation to growth and ion accumulations as compared to seed and root stock propagated violet seedlings. This might be due to higher SA concentrations in direct regenerated seedlings which resulted from somaclonal variations or growth media applied during tissue culture technique

What molecular mechanism is adapted by plants during salt stress tolerance?

Salt stress harmfully shocks agricultural yield throughout the world affecting production whether it is for subsistence or economic outcomes. The plant response to salinity consists of numerous processes that must function in coordination to alleviate both cellular hyper-osmolarity and ion disequilibrium. Salt tolerance and yield stability are complex genetic traits that are difficult to establish in crops since salt stress may occur as a catastrophic episode, be imposed continuously or intermittently and become gradually more severe at any stage during development. Molecular biology research has provided new insight into the plant response to salinity and identified genetic determinants that effect salt tolerance. Recent confirmation that many salt tolerance determinants are ubiquitous in plants has led to the use of genetic models, like Arabidopsis thaliana, to further dissect the plant salt stress response. Since manyof the most fundamental salt tolerance determinants are those that mediate cellular ion homeostasis, this review will focus primarily on the functional essentiality of ion homeostasis mechanisms in plantsalt tolerance. The transport systems that facilitate cellular capacity to utilize Na+ for osmotic adjustment and growth and the role of the Salt-Overly-Sensitive (SOS) signal transduction pathway in the regulation of ion homeostasis and salt tolerance will be particularly emphasized. The objective of the review is to know “What molecular mechanism is adopted by plants during salt stress tolerance?” A conclusion will be presented that integrates cellular based stress signaling and ion homeostasis mechanisms into a functional paradigm for whole plants and defines biotechnology strategies for enhancing salt tolerance of crops