National Defence University, Pakistan

About: National Defence University, Pakistan is a education organization based out in Islamabad, Pakistan. It is known for research contribution in the topics: Context (language use) & Decision support system. The organization has 802 authors who have published 816 publications receiving 3701 citations. The organization is also known as: National Defence University of Pakistan & National Defence University Islamabad.

Review on Relative Navigation Methods of Space Vehicles

Abstract: This paper is devoted to understanding relative navigation models that are used for space vehicles. The relative navigations models and approaches which are based on different systems (Inertial Navigation Systems (INS)&Global Navigation Satellite System (GNSS) , Laser&INS, Vision- Based, etc.) are compared. These models and approaches can be used individually or combined for solving relative navigation problems. Advantages and disadvantages of the models vary according to the usage area, platform type, and environment. Different methods and approaches exist in addition to different estimation and optimization algorithms for adaptation, control, and sensor fusion. Most of the models assume perfect attitude conditions. This study considers satellites' position estimates according to each other within formation on the Low Earth Orbit (LEO). Also, the aim of this article is to understand correlation between the relative navigation systems and the effectiveness of the algorithms which are used for estimating states during constellation or formation flight.

Biomechanics of a Rifle-Firing Model: Effects of Rifle Dynamics on Target Accuracy

Abstract: We present a mathematical model of a shooter’s position while firing a rifle. The biomechanical effects of rifle dynamics on the shooter in terms of joint loading and the distribution of forces exerted by the rifle among the right and left upper arms and forearms were investigated. The shooting position can be optimized from the kinematic parameters thereby calculated. These thorough kinetic and kinematic analyses can benefit the Malaysian military and sportsmen in terms of improved shooting performance, reduced injuries and cost savings. Kane’s method is applied in the formulation of the dynamic equations of motion and the inverse dynamic method is used to calculate the forces and torques in the system.

Physical and conductivity studies of plasticised methyl cellulose-lithium triflate based polymer electrolyte

Abstract: Solid polymer electrolyte based on methyl cellulose (MC)-lithium triflate (LiCF3SO3) plasticised with ethylene carbonate (EC) was prepared using solution cast technique. The X-ray diffraction (XRD) studies proved that the amorphous nature of the electrolyte systems was increases due to the addition of salt and plasticiser. The improved surface morphology of plasticised polymer system ensures it has good electrode-electrolyte contact during performance testing. The polymer electrolyte was found to have high thermal stability indicating that the electrolyte can be used at higher temperature. The ionic conductivity increased up to 1.24 x 10-4 S cm-1 at optimum amount of EC plasticiser associated to the effect of plasticiser that initially leads to the formation of Li+-EC complex. Consequently, it reduces the fraction of polymer-Li+ complex which contributes to the increase of the segmental chain flexibility in the plasticized system. Temperature dependent studies indicate ionic conductivity increase due to the temperature increase and is in line with Arrhenius behaviour pattern. An activation energy of 0.26 eV at highest conductivity sample was obtained. The addition of plasticiser lowers the activation energy thus increasing the ion mobility of the system and contributing to ionic conductivity increment. The plasticization method is a promising means to dealing with the solid polymer electrolyte problem and producing electrolytes that meet the needs of electrochemical devices.

Research of remote fault diagnosis technique based on Web-model

Abstract: The remote diagnosis based on web-model provides a convenient method for the equipments fault diagnosis in the way oflong- distance, network, multi-expertcooperationand shared resource. A framework, function module and its pointsof remote fault diagnosis are analyzed, and the advantage of web-model-based remote fault diagnosis is indicated sufficiently. At last the development and appli- cation of the prototype system prove the technique is feasible and effective.

Sintesis nanozarah kuprum dalam larutan kitosan menggunakan kaedah sinaran gama

Abstract: Kesan penggunaan kitosan terhadap nanozarah kuprum (Cu) yang disintesis menggunakan sinaran gama sebagai sumber agen penurunan telah dijalankan dalam sistem akues. Dos sinaran terserap yang digunakan adalah 50 kGy manakala penambahan isopropanol adalah penting sebagai penggarut kepada radikal pengoksidaan serta meningkatkan peranan agen penurun yang terhasil daripada proses radiolisis. Analisis serapan optik-UV telah mencirikan sifat optik larutan nanozarah Cu yang disintesis. Ketulenan fasa kristal nanozarah Cu yang terbentuk dalam matrix kitosan telah dibuktikan dengan pembelauan sinar-X (XRD). Berdasarkan imej mikroskop imbasan elektron (TEM), nanozarah Cu yang terhasil adalah berbentuk sfera dengan julat saiz 6-10 nm kecuali nanozarah Cu yang disintesis dalam kepekatan kitosan 0.3% w/v yang menunjukkan taburan bentuk yang tidak sekata. Analisis spektrofotometer transformasi Fourier inframerah (FTIR) yang dijalankan telah mengesahkan kehadiran sebatian kitosan dalam sampel nanozarah Cu dengan kepekatan kitosan 0.1 dan 0.3% w/v. Kajian ini mendapati penggunaan kitosan dapat melindungi nanozarah Cu daripada pengoksidaan oleh persekitaran. Saiz nanozarah juga didapati meningkat seiring dengan peningkatan kepekatan kitosan yang digunakan.