A honeycomb panel consists of an array of open hexagonal cells which their walls are perpendicular to face sheets although other panel sandwiches don’t have these perpendicular walls. Their design is often performed based on minimum weight. This research is aimed at minimizations of weight by means of computing honeycomb core girth. Weight optimization is done by means of Naive and numerical procedures. Numerical optimization is done by the sequential quadratic programming (SQP) method. Geometric parameters and optimized weight are calculated for hexagonal and square cells. Optimized weights for these two cross-sections are compared.

In this paper, a parametric study of Compressor performances is performed by the streamline curvature method. Effects of three input parameters in the design process, e. g., number of blades, distribution of blade thickness, and blade sweep angels, on the main objective parameters in the aerodynamic design, e. g., velocity distribution, efficiency, and pressure ratio, are investigated in the parametric study. Initially, a certain two-stage axial Compressor is designed by the streamline curvature method. Validation of the results is confirmed by comparing the obtained results with the experimental ones. Regarding various values for the aforementioned input parameters, the first stage of the axial Compressor is redesigned, and the output parameter is established. Therefore, the sensitivity of the design results to each of the aforementioned parameters is recognized. Results show that increasing the blades sweep angle causes the flow behavior, such as efficiency and pressure ratio in the axial fan, to improve while reducing it provides a completely contrary result. Also, reducing the rotors blades number leads to an increase in the pressure ratio and efficiency while its increase causes a contrary result. It is concluded that a reduction in the number of the blades has a stronger effect on the performance parameters than when it increases. The results also show that the effect of the thickness in the hub is greater than the thickness of the tip, and its increase leads to reduce both efficiency and pressure ratio.

Improving the efficiency of Compressors has been one of the most important goals of researchers over the years. In this paper, three different methods are presented for parameterization and blade optimization of axial flow Compressor. All methods consist of flow analysis tool, optimization algorithms, and parametric geometry generation tool that are different in each approach. An objective function is defined based on the aerodynamic performance of blade in the acceptable incidence angles range. A double circular arc blade is used as the initial guess for all methods. The performance of optimized blades and the initial blade are compared to evaluate the capability of various methods, and a good agreement is achieved. The results show that the level of performance improvement in each method depends on the number and type of the chosen parameters. All three methods have improved blade performance at the design incidence angle. However, only the first method shows significant performance improvement in off-design conditions.

Compressors are widely used in realization of multi-operand addition as well as the reduction of multiplication tree. One of the major properties of 4-2 Compressor is compression degree of two. 4-2 Compressors are used in order to design and implement larger Compressors such as 6-2, 9-2 and IEEE 754 standard (27-2 Compressor). The inconvenient of conventional 4-2 Compressor is the incapability of handling the signed numbers. In this paper a new technique for addition is proposed. Using this method and current mode multiple valued logic we propose a new circuit. It enjoys the 2's complement property and preserves the conventional 4-2 Compressor reduction degree. This design is simpler to realize. The propagation delay in the best and worst cases is exactly the same. The number of transistor used is reduced which results in a reduction of power dissipation and chip area. The related circuits are simulated with HSPICE using 0.25mm technology. The simulation results confirm what we have darned.

Abnormalities in the vibrational behavior of driving motors and their side effects have always been a chief concern for home appliance manufacturers. Hermetic Compressors used in refrigerators are no exception in this matter. As a single-piston reciprocating machine with a crankshaft driven by a simple rotor-stator system, Compressors can have noticeable vibrational dissonances. The Compressor’s vibration is considered as a source of noise that can be transferred to other parts of the refrigerator and disturbingly excite them. Despite multiple studies to isolate this vibration by removing or optimizing its pathways, the focus has never been directly on reducing the vibration of the main source. In this study, a 6 Degree of Freedom model of a refrigerator Compressor is derived and then simulated in MATLAB-Simulink. The model is then verified with the computational results of an equivalent model made in ADAMS. All vibrating parts and their indexes are identified in order to design a new suspension system with improved vibrational behavior. A genetic algorithm is used to minimize an acceleration-based objective function considering six optimization variables including the stiffness parameters of springs and their arrangement. The optimized springs were built and tested under an actual Compressor, and the time/frequency responses of the Compressor were compared with the initial system. The results show the enhanced vibrational behavior of the Compressor in its working frequency after optimization.

In this research, the aerodynamic design of a centrifugal Compressor is carried out using an inverse design method. At the first step of the aerodynamic design, the shape modification capability of Compressor meridional plane is generated by linking up the Ball-Spine inverse design algorithm as a shape modification algorithm and quasi 3D analysis code as a flow solver. Then, the meridional plane is modified by improving the hub and shroud pressure distribution and applying it to the inverse design code. At the second part of this research, by developing a novel design method on the blade to blade plane, and incorporating it into the quasi 3D flow solver, the 3D profiles of impellers will be obtained in order to reach the higher blade loading. Finally, to check the outcome of design process, the current and the modified impellers are analyzed using the full 3D flow solver, CFX. The results are the representatives of about 5 percent enhancement in Compressor total pressure ratio.

This study, primarily reports the development of a 3D design procedure for axial flow tandem Compressor stages and then the method is used to design a highly loaded tandem stage. In order to investigate the effects of such arrangement, another stage with conventional loading with single blade for both rotor and stator rows is designed with similar specification. In order to ease the comparison of results, chord lengths and hub/shroud geometries are selected with the same dimensions. At the next stage a three dimensional numerical model is developed to predict the characteristic performance of both tandem and conventional stages. The model is validated with the experimental results of NASA-67 stage and the level of the accuracy of the model is presented. Employing the model to simulate the performance of both stages at design and off design operating points show that, tandem stage can provide higher pressure ratio with acceptable efficiency. In another word, tandem stage is capable having the same pressure ratio at lower rotational speed. The safe operation domain and loss mechanism in tandem stage are also discussed in this report.

Recently a new inverse design algorithm has been developed for the design of ducts, called ball-spine (BS). In the BS algorithm, the duct walls are considered as a set of virtual balls that can freely move along some specified directions, called ‘spines’. Initial geometry is guessed and the flow field is analyzed by a flow solver. Comparing the computed pressure distribution (CPD) with the target pressure distribution (TPD), new balls positions for the modified geometry are determined. This procedure is repeated until the target pressure is achieved. In the present work, the ball-spine algorithm is applied to three-dimensional design of axial Compressor blades. The design procedure is tested on blades based on NACA65-410 and NACA65-610 profiles and the accuracy of the method is shown to be very good. As an application, the pressure distribution of the blade with NACA65-610 profiles is modified and the pressure gradient in the aft part of the blade is decreased and selected as target pressure distribution. The corresponding geometry which satisfies the target pressure is determined using the BS design algorithm.

With advancements in electronics technology, the need for faster processing and data storage has increased. As the scaling of metal-oxide-semiconductor field-effect transistor (MOSFET) technology has progressed, the industry has faced various challenges, including increased short-circuit effects, reduced gate control, exponential leakage current, and power dissipation. Field-effect transistors made from carbon nanotubes are a suitable replacement for MOSFETs. 4-to-2 Compressors are among the most popular bit compression cells that are widely used in multiplication or multi-operand addition. Their most important function is to increase the performance and efficiency of multiplication compression calculations. After examining twelve different 4-to-2 Compressor designs from various research papers, this article presents a novel 4-to-2 Compressor architecture utilizing modified logical relationships and carbon nanotube technology. The proposed 4-to-2 Compressor and other designs from the literature have been implemented using the HSPICE simulation software. The proposed design and the previous Compressors have been compared in terms of power consumption, delay, transistor count, and accuracy. Simulation results demonstrate that the new Compressor architecture achieves a 25% reduction in power consumption, an 18% decrease in delay, and a 12% reduction in transistor count compared to the best previous Compressor.

The choice of geometrical shape of the blades has a considerable effect on aerodynamic performance and flow characteristics in axial Compressors. In this paper, the effects of the blades shape on the aerodynamic design characteristics are investigated based on Streamline Curvature Method (SCM). Initially, the Streamline Curvature Method (SCM) is used for designing a two-stage axial Compressor. Comparing the current results with experimental ones indicates good agreement. The first stage of the axial Compressor is selected with three different blade profiles. The first case (case I) has the polynomial camber with naca thickness distribution series 6. The second case (case II) has the standard naca profile series 6 and the third case (case III) has the modified standard naca profile series 4. Results reveal that using the standard airfoils in the stators leads to improved flow conditions such as loss coefficient and pressure ratio. On the contrary, this profile selection may cause an increase in the stagger angle that is not favorable. Aerodynamic design with a polynomial camber line in the rotor demonstrates a better aerodynamic behavior in loss coefficient, pressure ratio and diffusion factor. Whilst the use of such a camber line in the stator leads to the formation of less favorable aerodynamics conditions in comparison to the standard airfoil.