Search

Bats colliding with spinning wind turbine blades result in bat mortality. Carcass surveys at individual wind turbines vary from daily to once a week and from large cleared plots to only the road and pad area. A physics‐based model is proposed to guide carcass surveys, for designing curtailment studies to detect treatment fatalities and for improving fatality estimates by accounting for unsearched areas. The model considers the effects of carcass size, weight, and drag, and it accounts for the turbine rotor size and rotation rate to simulate the trajectory of a carcass after it is struck by a wind turbine blade. A carcass parameter is defined as the ratio of drag force to body weight, which accounts for the relative effect of bat biophysical and aerodynamic characteristics. By applying restrictions on carcass survey and turbine yaw data, a limited sample of bat fatalities was obtained, and the analysis revealed that bats fall downwind of wind turbines, indicating wind drift significantly influences carcass fall trajectories. The new ballistics model includes the effect of wind drift on fall trajectory of a carcass. The model was used to investigate the sensitivity of carcass fall trajectories to variability of the input parameters. The tests showed that larger values of the carcass parameter, that is, when drag dominates, such as for small carcasses, resulted in larger downwind drift, whereas large carcasses with smaller carcass parameter values resulted in larger distances within the rotor plane. The relationship of wind speed and RPM was found to influence the carcass downwind distance more compared to the within rotor plane distance. Using carcass survey data, turbine operation data, and wind speed records, for seven bats surveyed the day after colliding with a wind turbine, modelled back‐trajectories were used to identify the likely strike location on the rotor. The model can be improved by validating the modelled trajectories with the recorded bat‐blade strikes in thermal videos. It should be noted that the findings of the present study are based on the bat fatalities that met strict criteria leading to small sample size and hence requires further evaluation for testing the robustness of the model.

Firearm injuries are a preventable epidemic in the USA. Extremities are commonly affected in gunshot injuries. Such injuries may be complex with concomitant osseous, soft tissue, and neurovascular components. The maximum wounding potential of a projectile is determined by its kinetic energy and the proportion of the kinetic energy that is transmitted to the target. Accurate assessment of ballistic injuries is dependent on utilizing the principles of wound ballistics, accurate bullet count, and ballistic trajectory analysis. The goals of this article are to review wound ballistics and the imaging evaluation of extremity civilian firearm injuries in the adult population, with emphasis on ballistic trajectory analysis, specific ballistic fracture patterns, and diffuse, secondary soft tissue ballistic injuries.

This paper presents the results of the theoretical external ballistic calculations for projectiles fired from barrels which correspond to the barrels used in two Polish small arms systems: MSBS- 5.56 system (MSBS GROT standard rifle and MSBS GROT carbine) and BERYL system (BERYL standard rifle and MINI BERYL carbine). The results obtained allowed the analyse of the effects of barrel length and the associated initial projectile velocity on the nature of projectile trajectory, particularly the over height and projectile range obtained along the trajectories. The analysis of the results facilitated an assessment of the scope of proposed changes in the settings of the firearm sights, resulting from the use of barrels of different lengths and the consequential changes in projectile trajectory.

Because of its excellent insulation capability, the usage of a silica-phenolic charring ablator as a nozzle liner is a common practice in the solid rocket motor industry. During the design of a solid rocket motor employing a silica-phenolic nozzle liner, it is desired to conduct an accurate analysis yielding in-depth thermal response and recession characteristics. As the interior ballistics and nozzle recession rate mutually interact, the best practice is to perform a coupled solution to both. Commonly used one-dimensional analysis tools with empirical approaches for estimation of convective heat transfer rate and blowing effect generally lack sought accuracy and do not model the transient shape-change phenomenon, which affects the nozzle performance. This Paper considers governing equations for charring, including pyrolysis gas injection and surface energy balance for melting ablation, along with a boundary condition governed by interior ballistics, and demonstrates a framework in which these equations are solved with governing equations for the nozzle flowfield in a coupled manner. Development and validation of a one-dimensional material response solver based on the same governing equations is also demonstrated. Also, results from a static firing test conducted with a small-scale ballistic evaluation motor employing a silica-phenolic nozzle insert are provided. Results from both investigations are compared and discussed.

The identification of firearms from forensic ballistics specimens is an exacting and intensive activity performed by specialists with extensive experience. The introduction of imaging technology to assist the identification process of firearms has enhanced the ability of forensic ballisticians to conduct analyses of these specimens for identification. The positive identification of ballistics specimens from imaging systems are important applications of technology in criminal investigation [1] [2] [3] [4]. While the image capture methodology for persons and forensic ballistics specimens is similar, the process of identification for each is dependent upon the level of certainty required for the identification. The forensic identification of ballistics specimens relies on the detection, recognition and ultimate matching of markings on the surfaces of cartridges and projectiles made by the firearms [5]. Traditional methods for the comparison of these marks are based on incident light microscopy. The image formed from the oblique illumination of the mark gives a representation of the surface of the specimen in the region of the mark [6]. This representation is critically dependent on the material of the surface on which the marks have been made, and the geometry and intensity of the illumination system. The assessment by the ballistician of the similarity between comparable marks on respective ballistics specimens from crime scenes and test firings will be based on the expertise and experience of the technologist. Thus the traditional method of matching markings has inherent difficulties, and entails an element of subjectivity [7]. The need for firearm identification systems by police services continues to increase with greater accessibility to weapons in the international contexts. The characteristic markings on the cartridge and projectile of a bullet fired from a gun can be recognized as a fingerprint for identification of the firearm [8]. Forensic ballistics imaging has the capacity to produce highresolution digital images of cartridge cases and projectiles for matching to a library of ballistics images [9]. However, the reliance upon imaging technologies makes identification of ballistics specimens both a demanding and exacting task, where the control of the error of

Hybrid rocket engines (HREs) are a chemical propulsion system that nominally combine the advantages of liquid-propellant rocket engines (LREs) and solid-propellant rocket motors (SRMs). HREs in some cases can have a higher specific impulse and better controllability than SRMs, and lower cost and engineering complexity than LREs. For HREs and SRMs, both kinds of rocket engine employ a solid fuel grain, and the chosen grain configuration is a crucial point of their design. Different grain configurations have different internal ballistic behavior, which in turn can deliver different engine performance. A cylindrical grain design is a very common design for SRMs and HREs. A non-cylindrical-grain is a more complex grain configuration (than cylindrical) that has been used in many SRMs, and is also a choice for some HREs. However, while an HRE and an SRM can employ the same fuel grain configuration, the resulting internal ballistic behavior would not be expected to be the same. Pressure-dependent burning tends to dominate in SRMs, while axial flow-dependent burning tends to dominate in HREs. To help demonstrate in a more direct manner the influence of the differing combustion processes on the same fuel grain configuration used by an HRE and SRM, a number of internal ballistic simulations are undertaken for the present study. For the reference SRM cases looked at, an internal ballistic simulation program that has the capability of predicting head-end pressure and thrust as a function of time into a simulated firing is utilized for the present investigation; for the corresponding HRE cases, a simulation program is used to simulate the burning and flow process of these engines. For the present investigation, the two simulation programs are used to simulate the internal ballistic performance of various HREs and SRMs employing comparable cylindrical and non-cylindrical fuel grain configurations. The predicted performance results, in terms of pressure and thrust, are consistent with expectations that one would have for both propulsion system types.

In order to achieve multi-objective optimization design of ballistics and improve the power of weapons, an optimization model for the internal ballistic simulation design of the propellant charge was established. Based on the requirements of artillery ballistic performance, the model took several influences into account, such as type, charge mass (ω) and web thickness (2e1). The objective function was composed of muzzle velocity (v0), maximum chamber pressure (pm), relative burnout point (ηk) equations. The computational program used recursive algorithm to calculate and select reasonable charge results by looping the internal ballistics and optimization design equation sets. 105 mm artillery and 122 mm artillery were selected as examples to optimize the charge design. The results show that compared with the existing charging scheme, the loading scheme optimized by the model can reduce the relative burnout point of 105 mm artillery by 0.21 in the case of the muzzle velocity, and the maximum chamber pressure have a little difference. The maximum chamber pressure of the 122 mm artillery reduces by 2.83% while the muzzle velocity increases by 1.13%.

Описывается программное обеспечение поддержки расчета внешней баллистики для оружия калибра 5,45 мм с учетом внешних факторов тактического тренажера оптико-электронного для стрелкового оружия «Ингибитор», разработанного в Институте механики УдмФИЦ УрО РАН и на кафедре «Вычислительная техника» ИжГТУ имени М. Т. Калашникова совместно с АО «Концерн «Калашников». Приводится тактико-техническое задание для баллистического расчета траектории до 2 км дальности имитаторов оружия с лазерным излучателем точки прицеливания с учетом внешних факторов: положения прицельной планки всех видов прицелов, температуры и давления воздуха, которые оказывают существенное влияние на сопротивление воздуха. Реализованная дифференциальная математическая модель внешней баллистики, опираясь на угол прицеливания имитатора оружия, начальную скорость и баллистический коэффициент боеприпаса в реальном времени, строит баллистическую траекторию с поправками на температуру и давление воздуха. Приводятся результаты испытаний программного обеспечения на погрешность расчета координат баллистической траектории. Сделан вывод о перспективности дальнейших исследований и разработке электронных стрелковых тренажеров благодаря совершенствованию и удешевлению элементной базы и развитию программных библиотек с целью повышения точности имитации внешней баллистики тренажеров с учетом многих внешних факторов, расширения функциональных возможностей и снижения себестоимости и, значит, повышения конкурентоспособности.

According to the characteristics of small caliber grenade, this paper establishes its internal and external ballistic model, and studies the characteristics and basic rules of internal and external ballistic of grenade. The key factors affecting the accuracy of the distance model are analyzed, and the techniques and methods for determining the parameters of the distance model are studied. The measuring system and wireless setting system for the precise control of small caliber grenade blast point are designed. The theoretical method of controlling the blast point of projectile by DSP chip and improving the accuracy of distance determination is described. Finally, a wireless setting system is constructed based on related theories and sensors.