Abstract: Conceived as simple, cheap and highly efficient alternative to solid rocket motors, the compound rocket engines include a liquid feed line system, within which at least the minimal components are involved, like the liquid tank, the dislocation augmenter, the main release valve, the in-line check valve (ICV) and the injector head. Simplicity and reliability are the main requirements in designing and manufacturing the components and, in order to accomplish these requirements, the dynamics and transient behavior of the devices become the key features of the entire design. The transient of the ICV required primary attention as it needs to cut the reversed flow of the liquid in a definitely short amount of time, determined from the condition of a given liquid return delay stop into the internal feed duct (IFD) of the engine. This delay was also set to cover the condition of partial vaporization of the liquid within the ICV and the IFD of the system. Numerical simulations were performed under rational assumptions regarding the mechanical behavior of ICV parts, limited to a number of minimal elements that secure a smooth work of the device and a fast response to upwind and downwind liquid pressure variations. The basic parameters considered are the size of the parts, their densities, closely connected to the manufacturing materials involved, sealing and surface finishing technology used that outputs the viscous and friction properties of the device parts considered for simulation. The ORVEAL research is granted by Romanian UEFISCDI.
Abstract: As a part of the ORVEAL project, the brand new series of compound rocket engines MEC-80 is subjected to a line of restrictions imposed by the experiment plan, which add an extra weight to the definitely expensive phase of the experimental development of the new types of rocket engine. The direct way to reduce the development time and cost of the new powering systems was found in tediously defining the experimental plan, the variables involved, the nature of the pay-off polynomials and the technological solutions. For the specific case the technological and reliability related constraints are explored, that led to the definition of a reversed-vertical configuration of the thrust frame of the test stand and of the scale and support system of the thrust frame, with position-defined sensors for acquiring the thrust tensor value. Simplicity and reliability were the main requirements in designing and manufacturing the components of the test stand in the new environment of the recently enhanced CEZAR proving grounds of ADDA Ltd. in Fagaras, Transylvania. The ORVEAL research is granted by Romanian UEFISCDI financing authority.
Abstract: The paper presents a design method for the control system of a flying wing unmanned air vehicle (UAV). A modified loop-shaping type configuration is adopted for the controller synthesis such that maneuverability, robustness with respect to modeling uncertainty and sensitivity reduction performances are accomplished. A stabilizing output feedback control law minimizing the $L_1$ norm of the resulting system is determined. The proposed design algorithm is illustrated by a case study.
Abstract: This paper has a small part of notion of chevron and the process that helps reducing the noise pollution.
Based on the gas dynamic and geometrical parameters of a single flow jet engine one does a model of CFD data processing. In this process one observes the influence of chevrons on acoustic wave intensity produced by the jet .
One studies a series of tests on triangular chevrons: immersions, the influence of the number of chevrons in order to settle the influence of the geometrical parameters on the flow and on the jet acoustics.
Finally one presents the contribution of chevrons in noise pollution reduction.
Abstract: The interest upon real options method amplified in the last decade due to the higher level of uncertainty faced by some organizations (from the private and also the public sector) when the decision to make a strategic investment is required (in a competitive environment) or it is a external requirement of the organizational environment (ensuring security standards). The process of assessment of the option is developed by evaluating the potential benefits associated with the three possible scenarios under expansion, contract and wait options. The value of the real option is the result of the fuzzy mean. The possibility of obtaining values for each option permits the management to compare and choose the best decisions for efficient investment. The evaluation and investment planning aims to make better use of funds by reducing operating costs and uncertainty for potential gains and substantiate predictions about the performance of the strategy.
Abstract: This article presents the possibility of implementing a solution for efficiently using supercapacitors to power a CubeSat. The system achieves a full powered CubeSat only by using supercapacitors and no other energy backup method. There are presented both advantages and disadvantages of such implementation. The article shows how much energy and power is available for the entire system for a specific amount of time. The data was collected using COTS parts, digital oscilloscopes and DAQ systems. There was also created a demonstrative structure (both CAD and real) to simulate and test the real life integration of a supercapacitor within a CubeSat. The data figures only a small part of implementing a supercapacitor power system within a CubeSat, further research needed to be made in each individual case of CubeSat that will be developed using such power system method. The article provides some suggestions about the electronic parts that can be used to develop such system, and some approximations for being able to compute fast power and energy values when comparing different supercapacitors, or other parts that would directly influence the usage of such system.
Abstract: As a part of the ORVEAL project, a real scale laboratory model of the inertial platform for ADDASAT is developed by the joint ADDA and UPB teams, ensuring the capability of a three-axis attitude control demonstration in the ground laboratory that simulates weightlessness by low friction bearings. The study is part of the larger ADDA-UPB program for developing the low cost NERVA orbital system for applications in enhanced environmental policies and land resources surveillance. The ORVEAL research is granted by Romanian UEFISCDI financing authority.
Abstract: This paper presents the development of two different control techniques as an approach having to remove steady-state error present in the response of attitude of a mini unmanned aerial vehicle. A problem that arises when performing pole placement controller is the selection of the poles, the Bessel approximation allows the selection of the eigenvalues in function to a specified response time for a feedback pole placement controller and state estimator (observer). On the other hand presents an optimal control technique combined with Kalman filter to estimate the state affected by perturbations in the system, both cases using the integral effect to eliminate the steady state error.These two control laws has the property of responding to a desired response according to a time or state response desired.
Abstract: Recently there were patents on not switched gear continuously variable transmission (CVT) without hydro transformer. In transmission wheelwork with two degrees of freedom and one entrance is used. Adaptive mechanism of CVT provides possibility of output link movement with speed inversely to resistance force at constant input power. However the theoretical description of such transmissions is not convincing enough. Obviously at the basis of creation of adaptive transfers with two degrees of freedom essentially new regularity of mechanics lies. Purpose of present work is to formulate regularities of the mechanics allowing creating the adaptive-mechanical continuously variable transmission. The using of the found regularities will allow creating transmissions with mechanical adaptation to variable technological loading.