In this article Collision probability method is used to satellite Collision risk analysis. Among different methods introduced for determining Collision probability, Patera's (2005) and Chan methods are chosen to define Noor satellite Collision to the other space objects. According to criteria described in the article, Advanced Conjunction Analysis Tools of STK software applied for Collision risk analysis. The software, determine position of each object in space using Two Line Elements and appropriate propagation model according to altitude of the orbit. So Collision probability calculated by one of the cpllision probability methods. If derived prababilty is larger than 10-3, so its necessary to schdule for suitable maneuver to avoid Collision.

In this paper, a new fast algorithm for path planning and a Collision prediction framework for two dimensional dynamically changing environments are introduced. The method is called Time Distance (TD) and benefits from the space-time space idea. First, the TD concept is defined as the time interval that must be spent in order for an object to reach another object or a location. Next, TD functions are derived as a function of location, velocity and geometry of objects. To construct the configuration-time space, TD functions in conjunction with another function named "Z-Infinity" are exploited. Finally, an explicit formula for creating the length optimal Collision free path is presented. Length optimization in this formula is achieved using a function named "Route Function" which minimizes a cost function. Performance of the path planning algorithm is evaluated in simulations. Comparisons indicate that the algorithm is fast enough and capable to generate length optimal paths as the most effective methods do. Finally, as another usage of the TD functions, a Collision prediction framework is presented. This framework consists of an explicit function which is a function of TD functions and calculates the TD of the vehicle with respect to all objects of the environment.

Introduction: Usually osseointegration takes between three to six months after implant placement but patients are interested to have early loading. There are no definitive criteria for measuring bone mineral density (BMD), insertion torque (IT) (final torque force) and resonance frequency analysis (RFA) (primary implant stability) to determine exact loading time based on the relationship between the above-mentioned parameters. The aim of this study was to determine the relationship between IT, RFA and BMD in screw-type implants.Materials and Methods: This clinical trial was conducted on 18 patients who were candidates for ITI implant placement. Written consent was taken and jaw bone density was determined via a digital radiography technique before surgery. After implant placement, RFA and IT were measured. Fifty-five ITI implants of the total 62 implants placed were evaluated; the implants were 12 mm long with a diameter of 4.1 mm. Data was analyzed with Pearson’s test using SPSS.15 software (a=0.05).Results: There was a significant relationship between IT, RFA and BMD. Pearson’s test showed a correlation coefficient of 0.872 to 0.789 between the three parameters, indicating a strong relationship between them. The mean bone density was 1.468±0.042 g/cm2; the mean RFA was 66.01±2.2 ISQ and the mean IT was 34.62±3.33 N/cm2.Conclusion: Based on the results of the present study there is a significant relationship between, IT, RFA and BMD (p value=0.001).

Road traffic crash is a cause of unnatural death and occupies fifth position in the world as per WHO records. Road crashes in India are alarming in situation while road safety is professionally lacking and politically missing. Hyderabad city, the capital of newly formed Telangana State occupies sixth position in occurrence of road crashes. An attempt is made to understand which model is suitable for road crash prediction and estimation of Collision type which is influencing road crashes in the city. A retrospective observational study was conducted in the city of considering factors as roadway geometrics, traffic data and type of Collision. Regression models like Multiple Linear Regression, Poisson Regression, Logit Model and Multinomial Logistic Model are considered for arriving crash prediction models. The suitability of model is based on R2 and chi-square test. It is observed from the analysis through comparison of above model; Logit model has an R2 of 0.7 and is significant for chi-square test. Shoulder condition is an affecting factor for non-fatal crashes in the city which is ascertained by Logit model. Further analysis is also carried for arriving on type of Collision influencing on road crashes. It is observed from the results that sideswipe is more significant for road crashes.

In this paper, a precise propagation model which takes into account the effects of the atmospheric drag and gravitational harmonies is developed and presented using available Two Line Element (TLE) data. Moreover, the prediction of the trajectory of space objects (e.g. the operational and non-operational satellites and space debris) and their orbital data is performed. Then, the 2009 prominent Collision between the Cosmos 2251 and Iridium33 satellite is simulated and the maximum probability of their Collision is computed by implementing the propagation algorithm and probabilities Theory, and finally the results are discussed. Therefore, the precise position and velocity of each space object at any time, as well as their Collision probability will be determined, and if necessary, the time available to enact Collision avoidance maneuver will be obtained. The success and accuracy of an avoidance maneuver is affected by the precision of the propagation model, the exact computation of Collision probability, and finally the maneuver mechanism which are utilized.

A theoretical model is developed to consider the effect of demulsifier agent on demulsification of water-in-crude oil emulsion. A thermodynamic approach is considered to correlate the critical micelle concentration of a demulsifier to the Collision frequency function in population balance equation (PBE). Based on the proposed correlation, the Collision frequency function is modified to account the effect of demulsifier agent on water droplets coalescence. The water separation capability of a selected group of demulsifiers is investigated via the conventional bottle test method to obtain the adjustable parameter of the developed equation so that the absolute relative error of predicted demulsification efficiency and experimental data are considered as objective. Comparison between the model simulated results and the experimental data showed that the proposed model could appropriately reproduce the experimental data at different agent concentrations.

This research presents a risk-based Hotspots identification model at highway-rail grade crossings in Canada. Two sets of models were developed to predict Collision frequency and consequence at individual crossings. A two– dimensional graphic approach was adopted to combine these two models together to predict the risk at each crossing. Hotspots based on Collision history tended to be widespread in Canada, while the Hotspot list based on model prediction tended to cluster in the Prairie Region of the country for frequency and the eastern provinces of Ontario and Quebec for consequence. Most Hotspots identified based on Collision frequency are located in urban areas with high AADT, while the Hotspots by Collision consequence are mostly located in rural areas with high train speed.

Flow-acoustic feedback is one of the main types of noise in a cavity, is caused by the instability of the cavity shear layer and is enhanced through an acoustic-wave feedback mechanism. The flow characteristics of the cavity boundary/shear layer and the characteristic frequencies of the flow-acoustic feedback in the cavities are studied numerically, with aspect ratios ranging from 1/2 to 4/3. The freestream Mach number is equal to 0. 11, corresponding to an Re-based cavity length of 2. 1×105. Improved Delayed Detached Eddy Simulations combined with Ffowcs Williams-Hawkings acoustic analogy are used to simulate the flow and noise characteristics of the cavities. Auto-correlation analysis of flow field fluctuations is used to establish a link between the boundary/shear layer pressure fluctuations and flow-acoustic feedback noise. For the low aspect ratio cavities investigated in this paper, convection velocities along the shear layer development direction are obtained using wavenumber-frequency analysis. The deeper the cavity, the lower the shear layer flow velocity. Correspondingly, the characteristic frequencies of the narrowband noise generated by the flow-acoustic feedback shift linearly toward the low frequency band as the cavity depth increases. The results of the predicted noise characteristic frequencies obtained using wavenumber-frequency analysis and Rossiter's empirical formula are in agreement with the calculated results.