On the Friction Coefficient in the Numerical Simulation of Tidal Wave Propagation

Based on the analytical solution of one-dimensional simplified equation of damping tidal wave and Heuristic stability analysis, the precision of numerical solution, computational time and the relationship between the numerical dissipation and the friction dissipation are discussed with different numerical schemes in this paper. The results show that (1) when Courant number is less than unity, the explicit solution of tidal wave propagation has higher precision and requires less computational time than the implicit one; (2) large time step is allowed in the implicit scheme in order to reduce the computational time, but the precision of the solution also reduce and the calculation precision should be guaranteed by reducing the friction factor: (3) the friction factor in the implicit solution is related to Courant number, presented as the determined friction factor is smaller than the natural value when Courant number is larger than unity, and their relationship formula is given from the theoretical analysis and the numerical experiments. These results have important application value for the numerical simulation of the tidal wave.

Development Concept for Non Conventional Hybrid Engine

Environmental issues and the need for environment-friendly transport have always been a priority for the world due to ever increasing demand of modes of transport. So developing quick and eco friendly vehicle is the trend as of now with most manufacturers globally. There are numerous ways in which manufacturers have tackled these issues. Some of the common approaches undertaken are refinements of existing internal combustion engines. Like developing technologies such as direct injection, VVT (variable valve time), VTEC (variable valve time electronic lift), VGT (variable geometry turbines), reducing engine friction and weight, cam less engines, micro hybrids, etc But the best/optimum compromise between eco friendliness and urge to develop more power with good fuel economy and reduced emission is best met by the development of hybrid engines. Thermal and electric engines both have advantages and disadvantages that are often complementary. Combustion engines offer better range, power and ‘lunge’, but give out exhaust gas, although the current Euro IV norm place strict limits on these. Electric engines are zero-emission and offer very quick pick-up from a stopped position, but the batteries have low range and limited speed. So this complementation of both power trains is exploited in hybrid engines. Now conventional hybrids have many disadvantages such as being bulky with additional weight of battery packs and motors and other auxiliary transmission components, complex and dangerous electric systems, etc. So it is proposed to develop a non conventional hybrid engine which produces power at par with the conventional one and releases emission which is compatible with the stringent emission norms set for the conventional hybrids with considerably lucrative fuel economy comparable with the currently available hybrids in market and yet overcome the drawbacks of the conventional hybrid engines. Also the compact size of the hybrid engine that we propose makes it quite viable to fitted in small vehicles (like bikes, compact cars, etc) which further makes it a more promising technology that can be made available to common people across the globe and there by lead to a better transportation system for people of all class and need. The conceptualization basically includes modification of an inline twin cylinder or a v-twin 4-stroke gasoline engine as a preliminary step towards achieving the above proposed objectives.

Random Collocation Method (RCM)

Recently, young people’s concern on theory is becoming very poor. If there is a numerical procedure that is friendlier with theory, the distance between theory and calculation would be decreased much, and the interaction between them would become more active. When the geometry of the domain is simple, the traditional analytical method using function expansion is very convenient in many numerical problems. In many problems, it has given very useful solutions for various problems. However, its effectiveness is usually limited to simple geometries of the domain. In the past, a fusion of the analytical approach and computational one has not been pursued sufficiently. If it becomes possible, it may give a different paradigm for obtaining the numerical solution. In the present paper, an innovative idea named Random Collocation Method (RCM) is discussed on how to overcome the weak point of the traditional method by combining it with computational method. It is the purpose of the present paper to develop the simplest numerical method and to make the distance between the theory and numerical method as small as possible.

Real-Time Multi-Body Software for HIL Simulations

The Hardware in the Loop simulation is an useful instrument to simulate complex mechanical systems in which the subject of the test is an hardware component. The results of the simulation, closer to the real behavior of the system, are the main advantage of this approach. This application is often used during the design process to test components of a complex mechanical system before the development of the prototype (e.g. embedded systems). The literature examples show, in general, mathematical model finalized to the application. The objective of this work is focused on the development of a generic Multi-Body software for HIL applications. Some simulations examples, the dynamic of a slider-crank and of a McPherson suspension, are presented at the end of the paper.

Driver Differentiation With Seat Settings: Part II—Feasibility Study for US Household

The addition of user-customizable features to automobiles increases the need to differentiate among drivers so that each driver’s custom settings can be automatically applied. Part 1 of this study modeled driver component positioning as a function of the stature difference between sharing drivers. To fully understand the feasibility of this approach to driver identification, we need to model the distribution of stature differences in the population of sharing drivers. Monte Carlo simulation is used to simulate both population variability in stature and positioning and the effect of initial conditions on positioning are included. The simulation of 10,000 households showed that for 87% of target pairs, differentiation performance of fewer than 2% errors can be achieved, even when the drivers share a vehicle equally (the most difficult differentiation scenario).

Development of an Interactive Graphical User Interface (GUI) for EnergyPlus

In order to make EnergyPlus easier to use in China, VisualEPlus, a Chinese graphical user interface for the program, has been developed. VisualEPlus is designed to be generic, so that it can be used in any country, as well as be linked to other modeling tools and interfaces for EnergyPlus. VisualEPlus has three main modules: (1) a Building Loads Module for defining the building geometry, envelope, and space conditions that has been adapted from an existing DOE-2 interface (DOE2IN); (2) a HVAC System Module with a drag-and-drop feature for defining the HVAC system; and (3) a View Report Module with a reporting and visualization tool for EnergyPlus reports and outputs. This paper presents the background and development of VisualEPlus, describes its main functions and features as compared to other existing interfaces for EnergyPlus, and discusses plans for the further development of VisualEPlus.

Effect of High Pressure Post Injection on Soot and NO Trade-Off in a DI Diesel Engine

In DI Diesel engines NO and Soot trade off is an important challenge for Engineers. In this paper, at first, multiple injection strategy will be introduced as a useful way to reduce both NO and Soot emissions simultaneously. Then the effect of injection pressure in post injection on the engine emissions will be studied. Investigations have been conducted on DI diesel engine. To evaluate the benefits of multiple injection strategies and to reveal combustion mechanism, modified three dimensional CFD code KIVA-3V was used. Results showed that using post injection with appropriate dwell between injection pulses can be effective in simultaneously reduction of emissions. Based on computation results, NO reduction formation mechanism is a single injection with retarded injection timing. It is shown that reduced soot formation is because of the fact that the soot producing rich regions at the fuel spray head are not replenished by new fuel when the injection is stopped and then restarted. Also increasing injection pressure in post injection will reduce the Soot emission dramatically while NO is in control and it is due to increasing fuel burning rate in post injection pulse.

Analysis of Experimental Data From Ship Trajectories of Turning Circles in a Regular Seaway

The accurate prediction of the track of a ship maneuvering in a seaway is one of the most important tasks in seakeeping. Most ship maneuvering studies, both experimental and numerical, focus on maneuvering in calm water. Recently, Lin and Klamo (2010) used the Digital Self-consistent Ship Experimental Laboratory (DiSSEL) to study the ship track of a turning circle maneuver in a wave field. In that study, it was shown that their simulated ship trajectories had good agreement with experimentally measured tracks. This agreement motivated the following quantitative analysis of the experimental data to characterize the effects that wave impacts have on turning circle ship tracks. Our method involves describing the ship trajectories as sinusoids with time-varying means. We also estimate the uncertainty in the results from our analysis of the experimental measurements. The quantitative analysis shows overall agreement with Lin and Klamo (2010). New findings are also discussed such as changes in the distance and time to complete the maneuver as well as the speed and preferred directions of a drifting turning circle.

A Numerical Study of Traumatic Brain Injury Due to Ground Impact in an SUV-Pedestrian Crash Using Full-Scale Finite Element Models

A number of studies have worked on traffic injuries or traumas related to pedestrian impacts. However, most of them placed more focuses on traumatic injuries due to primary impact with a striking vehicle rather than those involved in secondary impact with the ground. In this study, a validated, human whole-body, pedestrian finite element model was utilized to investigate the potential risk of traumatic brain injury (TBI) relevant to the ground impact as well as primary head strike in an SUV-to-pedestrian collision. By conducting a set of numerical experiments at impact speed of 25 and 40 km/h with pedestrian’s pre-impact, transverse, traveling speed of 1.3 m/s, it was found that ground impact is likely to cause serious TBI even in a low impact speed level. Although the post-impact kinematics and subsequent kinetics were considerably unpredictable due to the intrinsic complexity of pedestrian impact, this finding also suggests that impact speed does not necessarily contribute to the severity of pedestrian TBI involving vehicle with a higher profile. In the future, an effective countermeasure for ground impact should be taken into account to reduce the risk of sustaining serious TBIs in pedestrian crashes.

Experimental Validation of the COMPACT Code in Data Centers

This paper summarizes the comparison of predictions by a compact model of air flow and transport in data centers to temperature measurements of an operational data center. The simplified model and code package, referred to as COMPACT (Compact Model of Potential Flow and Convective Transport), is intended as an alternative to the use of time-intensive full CFD thermofluidic models as a first-order design tool, as well as a potential improvement to plant-based controllers. COMPACT is based on potential flow and combined with an application of convective energy equations, using sparse matrix solvers to seek flow and temperature solutions. Full-room solutions can be generated in 15 seconds on a commercially available laptop, and an accompanying graphical user interface has also been developed to allow quick configuration of data center designs and analysis of flow and temperature results. Experiments for validation of the model were conducted at the HP Labs data center in Palo Alto, CA, which is in a traditional configuration consisting of inlet floor tiles feeding cold air between two rows of multiple server racks. Subsequently, air exits either through ceiling tiles or direct room-return to CRAC units located on the side of the room. Temperatures were recorded at multiple points along entering and exiting flow faces within the room, as well as at various points in cold and hot aisles, and are presented and compared to model predictions to assess their accuracy. Areas of greater and lesser accuracy are analyzed and presented, in addition to conclusions as to the strengths and weaknesses of the model. For some cases, the average predicted temperature along in-flowing rack faces was within one degree of the average measured temperature. However, the differences in temperature are not evenly distributed. The most pronounced variations between the model and room measurements were located in areas above server racks where recirculation was shown to most likely occur. In these areas, the predicted temperature was higher than experimental values; this can likely be attributed to the absence of buoyancy effects in the simplified potential flow model. Adaptations of the model and its configuration standards for more accurate temperature distributions are proposed, as well as investigations into the effect on temperature comparisons to idealized model output by unaccounted heat sources or flow phenomena.