Showing papers in "Sadhana-academy Proceedings in Engineering Sciences in 2007"
TL;DR: An OCR system developed for the recognition of basic characters in printed Kannada text, which can handle different font sizes and font types and can be extended for the Recognition of other south Indian languages, especially for Telugu.
Abstract: Optical Character Recognition (OCR) systems have been effectively developed for the recognition of printed characters of non-Indian languages. Efforts are on the way for the development of efficient OCR systems for Indian languages, especially for Kannada, a popular South Indian language. We present in this paper an OCR system developed for the recognition of basic characters (vowels and consonants) in printed Kannada text, which can handle different font sizes and font types. Hu’s invariant moments and Zernike moments that have been progressively used in pattern recognition are used in our system to extract the features of printed Kannada characters. Neural classifiers have been effectively used for the classification of characters based on moment features. An encouraging recognition rate of 96.8% has been obtained. The system methodology can be extended for the recognition of other south Indian languages, especially for Telugu.
71 citations
TL;DR: In contrast to widely held beliefs of transportation planners, there is actually no growth of mobility if counted in number of trips per person per day, no time saving by increasing speed in the system, and no real freedom of modal choice as mentioned in this paper.
Abstract: Technological determinism has become a kind of religion for many people since it appears to offer solutions for societal problems as never before in history. Transport is one of the fascinating technology branches developed during the last 200 years. Effortless movement over long distances has become possible for car users as long as cheap fossil energy is available. However, the effect of fast transport on urban structures and society was not taken into account when developing these technical means. Technologists and economists have used indicators for expected benefits of these fast transport modes without taking into account the real system effects on society and urban structures. Plausible assumptions and hopes instead of scientific understanding of the complex system are used in practice. In contradiction to widely held beliefs of transportation planners, there is actually no growth of mobility if counted in number of trips per person per day, no time saving by increasing speed in the system, and no real freedom of modal choice. Modal choice is dependent on physical and other structures, the artificial environment built by urban planners, transport experts and political decisions. The core hypothesis of traditional urban and transport planning ‘growth of mobility’, ‘travel time saving by increasing speed’ and ‘freedom of modal choice’ are myths and do not exist in the real urban and transport system. This is the reason why urban planning and transport planning based on traditional non-scientific assumptions is creating continuously not only more transport problems, but also environmental and social as well as economic problems all over the world, where these principals are applied. Urban transport planning in Europe, understanding the transport system and the solutions are presented in this paper.
52 citations
TL;DR: In this article, the acid resistance of a pozzolanic cement (CEM IV-A/32·5) compared with Portland cement was compared after 120 days of acid attack.
Abstract: Acidic attack represents a topic of increasing significance, owing to the spread of damages of concrete structures in both urban and industrial areas. Cement type is an important factor affecting performance of cement based materials in an aggressive environment. The goal of this study was to compare the acid resistance of a pozzolanic cement (CEM IV-A/32·5) with Portland cement (CEM I 32·5) that was made from the same clinker. For this purpose, 50mm mortar cubes were prepared with two different kinds of cement according to TS EN 196-1. After 28 days of hardening, the samples were immersed into four different concentrations of hydrochloric, nitric and sulfuric acid solutions for a period of 120 days. The changes in weight loss and compressive strength values for each acid solution within the test period were recorded. The acid resistance of mortars made from Portland cement was better than the pozzolanic cement incorporated samples after 120 days of acid attack.
46 citations
TL;DR: The evolution of experimental biomechanics and crash injury research is summarized briefly to show that they both play a major role in mitigating traffic deaths and injuries as discussed by the authors, whereas some 80% of traffic casualties in the world are outside the vehicle as pedestrians, cyclists and motorcyclists.
Abstract: The evolution of experimental biomechanics and crash injury research is summarized briefly to show that they both play a major role in mitigating traffic deaths and injuries Historically, the subject has been based largely in western countries and thus focused on vehicle occupants, whereas some 80% of traffic casualties in the world are outside the vehicle as pedestrians, cyclists and motorcyclists The subject is close to the regulatory process which controls vehicle design and is thus heavily influenced by government and industry, yet it is now in an expanding period because of new techniques to replicate the human frame’s response to impact forces New knowledge is likely to emerge from addressing population variations and combining real world accident investigations with experimental biomechanics The application of impact biomechanics to the vulnerable road users is of particular importance
44 citations
TL;DR: In this paper, the problem of scheduling parallel, nonidentical batch processors in the presence of dynamic job arrivals, incompatible job families and non-identical job sizes has been addressed and a few heuristic algorithms have been designed for maximizing the utilization of heat treatment furnaces of steel casting manufacturing.
Abstract: This paper addresses a research problem of scheduling parallel, nonidentical batch processors in the presence of dynamic job arrivals, incompatible job-families and non-identical job sizes.We were led to this problem through a realworld application involving the scheduling of heat-treatment operations of steel casting. The scheduling of furnaces for heat-treatment of castings is of considerable interest as a large proportion of the total production time is the processing times of these operations. In view of the computational intractability of this type of problem, a few heuristic algorithms have been designed for maximizing the utilization of heat-treatment furnaces of steel casting manufacturing. Extensive computational experiments were carried out to compare the performance of the heuristics with the estimated optimal value (using theWeibull technique) and for relative effectiveness among the heuristics. Further, the computational experiments show that the heuristic algorithms proposed in this paper are capable of obtaining near (statistically estimated) optimal utilization of heat-treatment furnaces and are also capable of solving any large size real-life problems with a relatively low computational effort.
44 citations
Abstract: The macroscopic trend of road traffic fatalities in any motorized country is described and predicted by the product of rather well fitting functions of time for the exponential decay of fatality risk per unit of traffic volume and the S-shaped Gompertz function of traffic volume growth. This product defines a single-peaked development of road traffic deaths, where its peak reaches earlier the sooner and faster a nation or region motorizes massively. Since in developing countries long series of traffic volume data are absent, another model for the fit and prediction of road traffic fatalities for developing countries is used, based on the relationships of income level per capita with road traffic mortality. Also this model implies that at some point in time road traffic deaths will start declining for ever, also worldwide. After empirically derived corrections for missing or incomplete data and police under-reporting, it is estimated that 1·2 million deaths and almost 8 million serious injuries are caused by road traffic worldwide in 2000. Using realistic income level predictions the new income-dependent model predicts markedly later and higher fatality peaks than the verified time-dependent model. It might be assumed that the developing countries could learn faster to increase their road safety by knowledge transfer from developed countries. Four prediction scenarios are specified for modified income-dependent models of road traffic death and serious injury developments up to 2050. Depending on the scenario the world total of road fatalities begins to reduce soon or only after 2035 with a global peak of about 1·8 million road traffic deaths, where the national fatality reduction starts later the lower the national income per capita is. Without the potentially achievable learning scenario the road fatality reductions in developed countries may not be enough to compensate the road fatality increases in developing countries, while road fatality increases may even occur after 2060 in countries with the lowest levels of income per capita.
39 citations
TL;DR: In this paper, experimental data on acoustic pressure measurements obtained over a wide range of conditions is reported for two simple geometries that are commonly studied for their combustion dynamics behaviour. But the data indicate regimes of flow-acoustic lock-on that signifies the onset of combustion instability, marked by the excitation of high-amplitude discrete tones of sound in the combustor.
Abstract: Experimental data on acoustic pressure measurements obtained over a wide range of conditions is reported for two simple geometries that are commonly studied for their combustion dynamics behaviour. These geometries are the confined bluff-body and the confined backward-facing steps. The data indicate regimes of flow-acoustic lock-on that signifies the onset of combustion instability, marked by the excitation of high-amplitude discrete tones of sound in the combustor. The high- speed chemiluminescence imaging of the combustion zone indicates heat-release- rate fluctuations occurring at the same frequencies as observed in the acoustic spectra. Attention is then devoted to the data obtained under cold-flow conditions to illustrate distinctly different behaviour than when combustion instability occurs, contrary to the commonly held view that the combustion process does not alter the underlying fluid mechanical processes under low-Mach number conditions.
39 citations
TL;DR: Modifying the density method to represent non-homogeneous traffic, which includes significant percentages of motorized, three-wheeler, motorized two-wheelers, and non-motorized traffic entities, one can derive more accurate passenger car units for Indian conditions.
Abstract: Traffic on Indian roads (both urban and inter-urban) consists of a variety of vehicles. These vehicles have widely different static and dynamic characteristics. The traffic is also very different from homogeneous traffic which primarily consists of motorized vehicles. Homogeneous traffic follows strict lane discipline as compared to non-homogeneous traffic. Western traffic planning methodologies mostly address the concerns of homogeneous traffic and therefore often prove inadequate in solving problems involving non-homogeneous traffic conditions as found in Indian cities. This paper presents studies conducted on non-homogeneous traffic. Section 1 presents a methodology to verify the continuity equation, the basic block of any traffic planning analysis. In § 2, the methodology developed is applied to modify the Highway Capacity Manual (HCM) 2000 density method to derive passengercar equivalencies (PCEs) or units (PCUs) for heavy vehicles and recreational vehicles. These PCUs appear as ‘ET’ and ‘ER’ in HCM tables. The density method assumes motorized, four-wheeler traffic, i.e., homogeneous traffic, and does not include motorized three-wheelers, motorized two-wheelers, and non-motorized traffic often present on Indian highways. By modifying the density method to represent non-homogeneous traffic, which includes significant percentages of motorized, three-wheelers, motorized two-wheelers, and non-motorized traffic entities, one can derive more accurate passenger car units for Indian conditions. Transport professionals can use these PCU values for accurate capacity, safety, and operational analysis of highways carrying non-homogeneous traffic.
36 citations
TL;DR: A parametric study was performed to investigate the effect of liner thickness and density on the contact forces, pressures and energy absorption during impact, and expanded poly styrene foam of density 24 kgm−3 gave the lowest contact forces.
Abstract: Finite element models of the head and helmet were used to study contact forces during frontal impact of the head with a rigid surface. The finite element model of the head consists of skin, skull, cerebro-spinal fluid (CSF), brain, tentorium and falx. The finite element model of the helmet consists of shell and foam liner. The foam is taken as elasto-plastic, the brain is assumed to be viscoelastic and all other components are taken as elastic. The contact forces and coup pressures with helmet on the head are much lower than in the absence of the helmet. A parametric study was performed to investigate the effect of liner thickness and density on the contact forces, pressures and energy absorption during impact. For 4 ms−1 velocity, expanded poly styrene (EPS) foam of density 24 kgm−3 gave the lowest contact forces and for the velocities considered, thickness of the foam did not affect the contact forces.
32 citations
TL;DR: In this paper, free vibration of beams with different boundary conditions is analyzed within the framework of the third-order shear deformation theory using Lagrange multipliers, and the results are compared with the previous results based on Timoshenko and Euler-Bernoulli beam theories.
Abstract: In this study, free vibration of beams with different boundary conditions is analysed within the framework of the third-order shear deformation theory The boundary conditions of beams are satisfied using Lagrange multipliers To apply the Lagrange’s equations, trial functions denoting the deflections and the rotations of the cross-section of the beam are expressed in polynomial form Using Lagrange’s equations, the problem is reduced to the solution of a system of algebraic equations The first six eigenvalues of the considered beams are calculated for different thickness-to-length ratios The results are compared with the previous results based on Timoshenko and Euler-Bernoulli beam theories
32 citations
TL;DR: In this article, an experimental study on incipient motion of gravel-bed streams under steady-decelerating flow is presented, and an effort is made to determine a simplified method for the estimation of bed shear stress in deceleration flow over fixed and mobile beds for use in field situations.
Abstract: An experimental study on incipient motion of gravel-bed streams under steady-decelerating flow is presented. Experiments were carried out in a flume with two median grain sizes, d
50 = 16.7 mm for a fixed-bed case and d
50 = 8 mm for a mobile bed case. In addition, an effort is made to determine a simplified method for the estimation of bed shear stress in decelerating flow over fixed and mobile beds for use in field situations. From the observation of eleven fixed-bed and nine mobile-bed velocity profiles, it is revealed that the parabolic law method (PLM) and the Reynolds stress method are comparable for estimation of shear velocity in general. Also, the results show that the shear stress distribution adopts a convex form over fixed and mobile beds. Due to this form the critical Shields parameter value for decelerating flow is less than the reported values in literature. This paper supports Buffington & Montgomery (1997) statement that less emphasis should be given on choosing a universal shields parameter, and more emphasis should be given on choosing defendable values based on flow structure.
TL;DR: In this article, an experimental investigation of the dynamics and control of the laminar separation bubbles which are typically present on the suction surface of an aerofoil at a large angle of attack is performed.
Abstract: This work is an experimental investigation of the dynamics and control of the laminar separation bubbles which are typically present on the suction surface of an aerofoil at a large angle of attack. A separation bubble is produced on the upper surface of a flat plate by appropriately contouring the top wall of the wind tunnel. First, a basic (unforced) separation bubble is obtained to set a benchmark for further experiments. Parametric study is done where the reference velocity is decreased to quantify its effect on the aspect ratio of the bubble. It is found that with decrease in Reynolds number, the height of the bubble increases at a greater rate than the length. This feature could be useful in characterising separation bubbles especially from the point of view of low Reynolds number aerofoil design. Artificial disturbance is introduced at two different initial amplitudes (infinitesimal and finite) upstream of separation location and hotwire anemometry is used to trace the wave packet as it is advected downstream. The evolution of wave packets is seen to take place in two distinct stages. Finite amplitude forcing causes periodic quenching of the bubble. Interestingly, even an infinitesimally small forcing is seen to modify and thereby control the separation bubble.
TL;DR: In this article, a forward-facing supersonic air jet for a 60° apexangle blunt cone at a flow Mach number of 8 was used to reduce the aerodynamic drag.
Abstract: Substantial aerodynamic drag, while flying at hypersonic Mach number, due to the presence of strong standing shock wave ahead of a large-angle bluntcone configuration, is a matter of great design concern. Preliminary experimental results for the drag reduction by a forward-facing supersonic air jet for a 60° apexangle blunt cone at a flow Mach number of 8 are presented in this paper. The measurements are carried out using an accelerometer-based balance system in the hypersonic shock tunnel HST2 of the Indian Institute of Science, Bangalore. About 29% reduction in the drag coefficient has been observed with the injection of a supersonic gas jet.
TL;DR: In this paper, the authors investigated time-dependent characteristics of scour holes around vertical wall abutments under clear water conditions with uniform bed materials and developed an empirical relation for temporal variation of the scour depth.
Abstract: Accurate estimation of the maximum possible depth of scour at bridge abutments is important in decision-making for the safe depth of burial of footings. Besides, investigation of the geometric features of scour holes around abutments provides useful information for the degree of scour counter-measure to be implemented against excessive scouring. Experiments have been performed to investigate time-dependent characteristics of scour holes around vertical wall abutments under clear water conditions with uniform bed materials. Temporal variations of scour depth and scour contours were measured. Using this information, an empirical relation was developed for temporal variation of scour depth. Additional relations were also derived for time-dependent volume and surface area of the scour holes around abutments. The findings of this study may provide useful information for preliminary design of abutment footings and placement details of armoring counter-measures, such as riprap.
TL;DR: In this article, the authors provided a critical note on the practices followed in India for estimating the design scour depth, and illustrated the limitations that exist in the existing codes of practice using examples.
Abstract: Well-laid foundation is mostly provided in road and railway bridges in India over large and medium-sized rivers. The age-old Lacey-Inglis method is used for estimation of the design scour depth around bridge elements such as pier, abutment, guide bank, spur and groyene. Codal provisions are seen to produce too large a scour depth around bridge elements resulting in bridge sub-structures that lead to increased construction costs. Limitations that exist in the codes of practice are illustrated in this paper using examples. The methods recently developed for estimation of the scour are described. New railway and road bridges are required to be built in large numbers in the near future across several rivers to strengthen such infrastructure in the country. It is strongly felt that provisions in the existing codes of practice for determination of design scour depth require immediate review. The present paper provides a critical note on the practices followed in India for estimating the design scour depth.
TL;DR: In this article, the exact solution of the governing equation of an isotropic rectangular plate with four clamped edges was examined in terms of trigonometric and hyperbolic functions.
Abstract: The examination of the exact solution of the governing equation of the rectangular plate is important for many reasons. This report discusses in exact solution of the governing equation of an isotropic rectangular plate with four clamped edges. A numerical method for clamped isotropic rectangular plate under distributed loads and an exact solution of the governing equation in terms of trigonometric and hyperbolic function are given. Finally, an illustrative example is given and the results are compared with those reported earlier. This method is found to be easier and effective. The results show reasonable agreement with other available results, but with a simpler and practical approach.
TL;DR: In this paper, the dispersion relation connecting the phase velocity with wave number is derived, and the variation of phase velocity and attenuation coefficients with wave numbers is graphically and discussed.
Abstract: A study of surface wave propagation in a fluid-saturated incompressible porous half-space lying under a uniform layer of liquid is presented. The dispersion relation connecting the phase velocity with wave number is derived. The variation of phase velocity and attenuation coefficients with wave number is presented graphically and discussed. As a particular case, the propagation of Rayleigh type surface waves at the free surface of an incompressible porous half-space is also deduced and discussed.
TL;DR: This report addresses issues in finite element human body models in evaluating pedestrian and occupant crash safety measures and investigates the effect of muscle activation due to voluntary and non-voluntary reflexes on injuries through finite element modelling.
Abstract: Conventional dummy based testing procedures suffer from known limitations. This report addresses issues in finite element human body models in evaluating pedestrian and occupant crash safety measures. A review of material properties of soft tissues and characterization methods show a scarcity of material properties for characterizing soft tissues in dynamic loading. Experiments imparting impacts to tissues and subsequent inverse finite element mapping to extract material properties are described. The effect of muscle activation due to voluntary and non-voluntary reflexes on injuries has been investigated through finite element modelling.
TL;DR: In this paper, the effects of confinement reinforcement on the behavior of high strength concrete columns were investigated for which prismatic experimental specimens were prepared, and the results showed that confinement reinforcement improved the ductility of high-strength concrete.
Abstract: The effects of confinement reinforcement on the behaviour of high strength concrete columns are investigated for which prismatic experimental specimens were prepared. In the experiment specimens, four longitude reinforcement and confinement reinforcement were used. For each experiment, stress-strain relationship of concrete was obtained and compared with models proposed earlier. The results show that confinement reinforcement improved the ductility of high strength concrete. The ascending branch of stress-strain curves depended on the ratio of confinement reinforcement was similar to the modified Kent-Park model and the descending branch similar to the Nagashima model.
TL;DR: In this article, the rollover propensity of a three-wheeled scooter taxi used extensively on SE Asian roads is analyzed using a rigid body mathematical model to simulate increasing steer, NHTSA J-turn, and Road Edge Recovery maneuvers.
Abstract: The rollover propensity of a three-wheeled scooter taxi used extensively on SE Asian roads is analysed in this report. A rigid body mathematical model was used to simulate increasing steer, NHTSA J-turn, and Road Edge Recovery maneuvers. The anomaly between public perception of the rollover susceptibility and available crash data has been resolved through finite element (FE) simulation. The optimum configuration of the vehicle and seating arrangement for varying numbers of passengers was determined. The safety of occupants and pedestrians in impact events was analysed through simulation in MADYMO TM , and cost effective
TL;DR: Performance of NSTFPI controller is compared with performance of fuzzy logic (FL) and fuzzy logic PI (FLPI) controllers in respect of rise time, settling time, overshoot and steady state error.
Abstract: In this work, the dynamic model, flux-current-rotor position and torque-current-rotor position values of the switched reluctance motor (SRM) are obtained in MATLAB/Simulink. Motor control speed is achieved by self-tuning fuzzy PI (Proportional Integral) controller with artificial neural network tuning (NSTFPI). Performance of NSTFPI controller is compared with performance of fuzzy logic (FL) and fuzzy logic PI (FLPI) controllers in respect of rise time, settling time, overshoot and steady state error.
TL;DR: In this paper, a massive concrete structure supported on a raft foundation is investigated based on seismic soil-structure interaction analysis of the structure and the results indicate tensile stresses of considerable magnitude at few locations in the rock-raft interface.
Abstract: Investigations conducted based on seismic soil-structure interaction analysis of a massive concrete structure supported on a raft foundation are presented in this paper. Linear transient dynamic analysis is carried out using finite element method and imposing transmitting boundary conditions at far field of layered elastic half-space. Analysis is conducted in two phases, namely: (i) free-field analysis of the layered half-space and (ii) seismic analysis of the structure by including soilstructure interaction effects. In the first phase, a simple and novel technique is used to establish free-field excitation at a depth in the half-space. In the second phase, seismic soil-structure interaction analysis of the structure is carried out for the free-field excitation determined in phase-I. Stress resultants experienced by the raft and the stresses at the interface between the rock and raft are evaluated. Critical examination of the results indicates tensile stresses of considerable magnitude at few locations in the rock-raft interface. Typical stress responses at the interface are presented and discussed in the paper.
TL;DR: In this paper, a long period grating (LPG) with a periodicity of 600 μm and grating length of 24 mm has been inscribed on a standard single mode fiber, which has been used in designing temperature sensors and temperature is monitored up to 80°C.
Abstract: Long Period Gratings (LPGs) have been developed using carbon dioxide laser in a standard optical fibre. LPGs with a periodicity of 600 μm and grating length of 24 mm have been inscribed on standard single mode fibre. Such gratings have been used in designing temperature sensors and temperature is monitored up to 80°C. The sensitivity of such type of sensor is 0·06 nm/°C where as for standard Fibre Bragg Grating (FBG) it is 0·011 nm/°C. The LPG performance is also evaluated after γ-ray irradiation for total dose of 5 KGy and has not shown any effect on transmission spectrum.
TL;DR: In this article, the aerodynamic properties of open window buses without air-conditioning were studied and the results showed that the air flow is highly three-dimensional and unsteady.
Abstract: Open window buses without air-conditioning are a major mode of urban and inter-city transport in most countries. High occupancy combined with hot and humid conditions makes travel in these buses quite uncomfortable. In this study air flow through a bus has been studied that could be the basis for low cost and eco-friendly methods of increasing passenger comfort and possibly reduce drag. The aerodynamics of such a road vehicle has not been studied as previous investigations have been confined to vehicles with closed windows that present a smooth exterior to air flow. Using a 1:25 scaled Perspex model of an urban bus in Delhi, flow visualization was performed in a water channel. The Reynolds numbers were one-tenth of a real bus moving at 10 m/s. Smoke and tuft visualizations were also performed on an urban bus at 40 km/h. Numerical simulations were performed at the actual Reynolds number. Even though there were Reynolds number differences, the broad features were similar. Air enters the bus from the rear windows, moves to the front (relative to the bus) and exits from the front windows. Inside air velocity relative to the bus is about one-tenth of the free-stream velocity. The flow is highly three-dimensional and unsteady.
TL;DR: A hybrid neural network model which combines the features of feed forward neural networks and genetic algorithms has been developed for the design of beam subjected to moment and shear with accuracy satisfying all design constraints.
Abstract: There is no direct method for design of beams. In general the dimensions of the beam and reinforcement are initially assumed and then the interaction formula is used to verify the suitability of chosen dimensions. This approach necessitates few trials for coming up with an economical and safe design. This paper demonstrates the applicability of Artificial Neural Networks (ANN) and Genetic Algorithms (GA) for the design of beams subjected to moment and shear. A hybrid neural network model which combines the features of feed forward neural networks and genetic algorithms has been developed for the design of beam subjected to moment and shear. The network has been trained with design data obtained from design experts in the field. The hybrid neural network model learned the design of beam in just 1000 training cycles. After successful learning, the model predicted the depth of the beam, area of steel, spacing of stirrups required for new problems with accuracy satisfying all design constraints. The various stages involved in the development of a genetic algorithm based neural network model are addressed at length in this paper.
TL;DR: In this paper, the authors used finite element technique to analyze the flow and temperature distribution in a two-dimensional steady state natural convection heat transfer problem in a bakery shop and found that placing the heater at the bottom of the oven improves the air circulation rate by 17 times and 10 times more than placing it at the top and side.
Abstract: The CFD analysis of flow and temperature distribution in heating ovens used in bakery shop, to keep the foodstuffs warm, is attempted using finite element technique. The oven is modelled as a two-dimensional steady state natural convection heat transfer problem. Effects of heater location and total heat input on temperature uniformity of foodstuffs are studied. Placing the heater at the bottom of the oven improves the air circulation rate by 17 times and 10 times than that at the top and side of the oven. But the top location provides better uniformity in foodstuff temperature than the other cases. Side location is not preferable. In the present ovens, the heating elements are located at the top. The analysis shows that if heaters are located at the bottom along with additional flow guidance arrangements, energy efficient oven configuration can be obtained.
TL;DR: In this article, the authors described the process of using finite element simulations to investigate safety options for motorcycle riders and concluded that inflating airbags in motorcycles do not pose a significant injury threat.
Abstract: The present standard for assessing the effectiveness of safety measures for motorcycle riders defined in ISO 13232 is unique and it incorporates evaluation by computer simulation supplemented by full-scale crash tests. This report describes the process of using FE (Finite Element) simulations to investigate safety options for motorcycle riders. The experience of developing finite element models acceptable as per ISO 13232 standards has been described. The variation in dummy head accelerations on impact with inflating airbags has been studied in an environment acceptable as per ISO 13232 standards. Based on the simulations, it may be concluded that inflating airbags in motorcycles do not pose a significant injury threat.
TL;DR: In this paper, the authors dealt with the determination of transient thermal stresses in a thick annular disc and derived the results for displacement and stresses in terms of Bessel's functions.
Abstract: The present paper deals with the determination of transient thermal stresses in a thick annular disc. A thick annular disc is considered having zero initial temperature and subjected to arbitrary heat flux on the upper and lower surfaces where as the fixed circular edges are at zero temperature. The governing heat conduction equation have been solved by using integral transform technique. The results are obtained in series form in terms of Bessel’s functions. The results for displacement and stresses have been computed numerically and are illustrated graphically.
TL;DR: In this article, a variable droop leading edge (VDLE) airfoil was used to control compressible dynamic stall through management of its unsteady vorticity.
Abstract: This study reports control of compressible dynamic stall through management of its unsteady vorticity using a variable droop leading edge (VDLE) airfoil. Through dynamic adaptation of the airfoil edge incidence, the formation of a dynamic stall vortex was virtually eliminated for Mach numbers of up to 0.4. Consequently, the leading edge vorticity flux was redistributed enabling retention of the dynamic lift. Of even greater importance was the fact that the drag and pitching moment coefficients were reduced by nearly 50%. The camber variations introduced when the leading edge was drooped are explained to be the source of this benefit. Analysis of the peak vorticity flux levels allowed the determination of minimum necessary airfoil adaptation schedule.
TL;DR: In this paper, the authors have paid little attention to public transport system pricing leading to the absence of a financially viable, self-supporting urban transport system, which is a symptom of the general process of rapid urbanization and environmental degradation.
Abstract: Urban transport has serious problems that are symptoms of the general process of rapid urbanization and environmental degradation. Policymakers in general and urban economists in particular have paid little attention to public transport system pricing leading to the absence of a financially viable, self-supporting urban transport system.