Offset agreements are legal trade practices, common in the aerospace and military industries. The international names for these commercial practices are various: industrial compensations, industrial cooperation, offsets, industrial and regional benefits, balances and equilibrium. An offset agreement is an agreement between two parties whereby a supplier agrees to buy products from the party to whom it is selling, in order to win the buyer as a customer and offset the buyer's outlay. Generally the seller is a foreign company and the buyer is a government that stipulates that the seller must then agree to buy products from companies within their country. Indeed, industrial compensation practices required as a condition of purchase in either government-to-government or commercial sales of articles and/or services. Often, the aim of this process is to even-up a country's balance of trade. Although the offset agreement is so significant, it has been rarely known for inner academic associations; in this work, after brief introducing of the mechanism, variations and compensatory obligations of these contracts, we discuss about the structure of them and the tendency of their parties to bind independent contracts related to each other throughout a document called the protocol.

In this study, an experimental and numerical analysis is done to study the flow characteristics of an offset and non-offset axisymmetric jet impingement on a circular cylinder. The purpose of this study is investigation of the behavior of the cutting gas jets and finding the optimum distance between nozzle and cylinder to achieve maximum cutting performance. Finite volume approach is used to solve the governing equations for a turbulent, incompressible jet numerically. According to the literature the suitable turbulence model for this purpose is realizable k-e. Velocity and pressure fields around the cylinder and pressure and shear stress distribution on the cylinder surface are determined for various cases. Also, some experiments are done to validate repeatability of experiments and numerical results. Comparisons between numerical results and experimental measurements validate the accuracy of numerical results. Also, results show that if the horizontal distance between the nozzle outlet and the stagnation point of cylinder is 2.5D, the shear stress on the cylinder surface has maximum value. Therefore in this situation jet has a maximum performance in cutting procedure.

It has been shown over several decades of radar research that the exploitation of diversity in a number of domains such as space, frequency, time, polarization, and, recently, waveform can provide increased agility, flexibility, reliability, and capabilities to the radar system. However this is often achieved either through efforts in system design, increased hardware complexity, or by employing additional resources. In the frequency diverse array (FDA) the subsequent antenna elements are fed with stepped discrete frequencies. So a range-angle dependent radiation pattern is made possible. It is possible to apply different frequencies with different patterns to the elements of FDA to achieve different radiation pattern. In this paper, a frequency diverse array with non-uniform inter-element frequency offset called quadratic-FDA has been proposed, that its variation is a function of physical distance of elements from the first element. To produce the coefficient of the frequency offset two Frequency offset generators has been proposed. In The first proposed method uses linear distance as a input of function and the second one uses multiples of the roots of the Chebyshev polynomial. The proposed strategy provides a non-periodic beampattern, with a maximum that can be steered in space by selecting appropriate excitation weights of the antennas. This single-maximum beampattern, in contrast to multiple-maxima beampattern of the other forms of FDA, can help to further reject range-dependent interferences, causing improved SINR and increased detectability.

Nowadays, computer simulations are becoming more and more important in performance investigation of thermal systems. In this article, radiator from a cooling system of a diesel engine of ER24PC locomotive is simulated. The radiator is composed of parallel and series arrangement of compact heat exchangers with offset strip fins. It also has two high and low temperature sections. Due to the complexity and compactness of heat transfer plates implemented in the radiator, the simulation is carried out in two steps. First, a relation for coolant-side and air -side heat transfer coefficient is correlated using computational fluid dynamics. Due to vortex shedding phenomenon in the staggered fin arrays, governing equations are solved transiently in twodimensional space. Appropriate timestep for the transient solution is chosen according to time period of vortex shedding from the surface. In the second step, using the developed computational code, the overall thermal performance of the radiator is simulated as a heat exchanger. Consequently, temperature distribution inside the radiator and its thermal performance are studied. Amount of heat released from the radiator in different flow rates and temperatures of fluid flowing out of the radiator are among the outputs of the developed code. Finally, thermal performance curve of radiator is obtained.

Stator flux oriented vector control of induction motor (IM) drives for speed sensorless control has several advantages. But the application of a pure integrator for the flux estimation is difficult due to the presence of measurement noise and dc offset. To overcome these problems, some have used a programmable cascaded low pass filter (PCLPF). In this paper, it is shown that some problems still exist and some new problems arise from this approach. In order to solve these problems, a novel compensation method is proposed. In this scheme, the dc offset is detected and subtracted from the estimated flux along d and q axes. The simulation results show that it works well in the low speed region as well as in the transient state. The oscillation of the torque and the estimated flux are also reduced notably when the torque reference changes rapidly.

In this paper, dynamic comparators structure, by employing two methods for power consumption reduction with applications in low-power high-speed analog-to-digital converters, have been presented. The proposed comparators have low consumption thanks to power reduction methods. They have the ability for adjusting the offset. The comparators consume 14. 3 and 24 μ W at 100 MHz, which is equal to 3. 7 and 11. 8 fJ. The comparators are designed and simulated in 180 nm CMOS. Layouts occupy 210 and 240 μ m2, respectively.

In this paper optimization of frequency offset estimation technique based on channel estimation, which is desirable for frequency selective channels and hasfast convergence speed, for using in HF channel is addressed. Because of time variations coherence time in HF channel is short, which leads to a severe degradation in the performance of above technique in this channel. An optimization of said technique is proposed in which after removing coarse frequency offset estimation and knowing residual frequency offset range, incorrect estimations can be removed and others can be averaged to give final correct estimate. Simulation is conducted underchannel parameters with respect to MIL-STD-188-110B. the results show that proposed optimization result in improved performance of frequency offset estimation technique based on channel estimation.

With the growing development of wireless communications systems, the use of systems with high data rates has arrested attention that can be noted to OFDM systems among these systems. The important features of this system are efficient usage of bandwidth and resistance to errors caused by the multipath propagation environment. OFDM systems have a high sensitivity to frequency offset. Due to the importance of signal eavesdropping in the cyber defence, in order to compensate frequency offset, it is necessary to use blind frequency estimation methods based on the inherent structure of the system and without the use of pilot symbols. Accordingly, in this paper, a blind frequency offset estimation algorithm based on cyclic prefix (CP) by using adaptive algorithms is presented that is closed to the optimum frequency offset during a step by step algorithm. In the proposed method, the Normalized Least Mean Square (NLMS) and Recursive least squares (RLS) adaptive algorithms are used to provide a method for estimating the frequency offset. The main feature of the new presented method is the ability to estimating the frequency offset in the presence of the time offset and in multipath channel with frequency-selective fading. According to the simulations results that are performed in the frequency-selective fading channel, MSE criterion in the NLMS proposed method about 3 dB and in the RLS proposed method approximately 7 dB has improved compared to other methods.