Cut Slot Research Articles

Numerical investigation of tip clearance designs for oblique-cut fin microchannels

Tip clearance represents a simple design intervention strategy to mitigate the high hydraulic penalties often associated with microchannel heat sinks. This approach has not been widely explored for enhanced microchannel heat sinks, having previously focused only on conventional (uniform) tip clearance design for straight microchannels. In view of this, the present work investigates the performance of an enhanced heat sink, specifically oblique-cut fin microchannels, with tip clearance designs. Two different designs are considered, namely conventional/uniform tip clearance (utc) and a newly conceptualized modulated tip clearance (mtc). Numerical simulations are conducted using ANSYS FLUENT 2022 R1 first for straight microchannels, which are considered the baseline to which oblique-cut fin microchannel designs are compared. The simulations are carried out under laminar flow regime including conjugate heat transfer in a heated solid substrate for flow rates of 250 – 650 mL/min. The results indicate that utc significantly reduces pressure drop though can increase thermal resistance for the oblique channels. The underlying physical mechanisms responsible for this observation are elucidated by examining thermal and flow behaviours in and around oblique cut slots. Based on the flow behaviour in oblique slots with utc, modulated tip clearance (mtc) concept is introduced and investigated. When compared to utc cases, mtc tends to reduce the thermal resistance substantially, though depending upon oblique cut angle and flow rate. However, the Performance Index (PI) shows that utc improves the overall performance in the range of 10–15 % compared to that observed with mtc cases, though the factor of improvement reduces closely to 5 % at 650 mL/min. In addition, the overall performance in terms of heat transfer and hydraulic pumping power further show that utc and mtc design strategies are competitive, and warrant further multi-objective optimization investigations to determine the best design option overall.

Enhancing High-Alloy Steel Cutting with Abrasive Water Injection Jet (AWIJ) Technology: An Approach Using the Response Surface Methodology (RSM).

The common machining technologies for difficult-to-machine materials do not remarkably ensure acceptable efficiency and precision in bulk materials cutting. High-energy abrasive water injection jet (AWIJ) treatment can cut diverse materials, even multi-layer composites characterized by divergent properties, accurately cutting complex profiles and carrying them out in special circumstances, such as underwater locations or explosion hazard areas. This work reports research on the AWIJ machining quality performance of X22CrMoV12-1 high-alloy steel. The response surface method (RSM) was utilized in modeling. The most influencing process control parameters on cut kerf surface roughness-abrasive flow rate, pressure, and traverse speed-were tested. The result is a mathematical model of the process in the form of a three-variable polynomial. The key control parameter affecting the cut slot roughness turned out to be the traverse speed. In contrast, pressure has a less significant effect, and the abrasive mass flow rate has the slightest impact on the cut slot roughness. Under the optimal conditions determined as a result of the tests, the roughness of the intersection surface Sq does not exceed 2.3 μm. Based on the ANOVA, we confirmed that the model fits over 96% appropriately with the research outcomes. This method reduces the computations and sharply determines the optimum set of control parameters.

Wire Electrical Discharge Machining of AISI304 and AISI316 Alloys: A Comparative Assessment of Machining Responses, Empirical Modeling and Multi-Objective Optimization

This research investigates the multi-response of both material removal rate (MRR) and surface roughness (Ra) for the wire electrical discharge machining (WEDM) of two stainless steel alloys: AISI 304 and AISI 316. Experimental results are utilized to compare the machining responses obtained for AISI 316 with those obtained for AISI 304, as previously reported in the literature. The experimental work is conducted through a full factorial experimental design of five running parameters with different levels: applied voltage, transverse feed, pulse-on/pulse-off times and current intensity. The machined workpieces are analyzed using an image processing technique in order to evaluate the size of cut slots to allow the calculation of the MRR. Followed by the characterization of the surface roughness along the side walls of the slots. Different mathematical regression techniques were developed to represent the multi-response of both materials using the MATLAB regression toolbox. It was found that WEDM process parameters have a fuzzy influence on the responses of both material models. This allowed for multi-objective optimization of the regression models using four different techniques: multi-objective genetic algorithm (MOGA), multi-objective pareto search algorithm (MOPSA), weighted value grey wolf optimizer (WVGWO) and osprey optimization algorithm (OOA). The optimization results reveal that the optimal WEDM parameters of each response are inconsistent to the others. Hence, the optimal results are considered a compromise between the best results of different responses. Noteworthily, the multi-objective pareto search algorithm outperformed the other candidates. Eventually, the optimal results of both materials share the high voltage, high transverse feed rate and low pulse-off time parameters; however, AISI 304 requires low pulse-on time and current intensity levels while AISI 316 optimal results entail higher pulse-on time and current levels.

SIMULATION OF UNDEFORMED CHIP FORMED DURING CUTTING FOR INTERNAL CROWN TOOTH BY THE "POWER SKIVING" METHOD

Today, the world's leading enterprises engaged in the manufacture of gear wheels increasingly use the Power Skiving method of cutting the gear crown on the wheel. This modern method allows you to process wheels with an external and internal crown, both spur and helical, as well as cut slots on shafts or hubs. This technology combines elements of turning and milling and ensures a very short production time. However, every year this method is increasingly improved, and in terms of its kinematics it is very complex and requires precise calculations. Determining the exact position of the tool and the workpiece at each moment of time is necessary for synchronizing movements during cutting. The principle of building an undeformed chip when cutting an internal straight-tooth crown by the Power Skiving method is shown. Section parameters for chip sections are obtained. They are the basis for modeling and calculating the values of cutting forces, friction, the necessary work that is needed to eliminate the allowance, heat flows that occur during cutting, the intensity of tool heating, temperature and wear of the tool, simulation of oscillations and dynamic processes. Complete information about the size and shape of the sheared layers, their size in different sections of the tooth at each moment of the cutting time is necessary for the description of various interrelated and interdependent deformation and contact processes. The established regularities of their continuous cyclical change during the revolution of the cutting tool are required for a comprehensive reproduction of the processes that occur during the cutting process of the toothed crown. A complex system of grapho-analytical, mathematical and computer modeling of this process has been developed for such a task. Kinematics is taken into account and the patterns of cutting-forming processes are reliably reproduced. The application of the grapho-analytical method of constructing sections for an undeformed chip is presented, which made it possible to establish its geometry and main characteristics, as well as to obtain a 3D model. Adequate models of chip formation are obtained. Quantitative estimates of parameters for slices in the process of Power Skiving are analyzed.

Experimental Investigation for the Prediction of Surface Roughness Height Parameters in Abrasive Water Jet Cutting of Kevlar/epoxy Composites

The main objective of the research was to study the influence of the abrasive water jet cutting (AWJC) parameters on the surface roughness parameters Rz1max and Rt, obtained when processing Kevlar fiber-reinforced polymers (KFRP). For this purpose, a full factorial experimental program was designed and roughness evaluations were carried out in two different zones of the cut slot. In this way, it was possible to test the statistical significance of the input parameters effects and characterize both these regions, by means of prediction models proposed for each roughness parameter. Finally, response surfaces and level curves were represented to facilitate the selection of proper factors combination to achieve surface finish requirements.

Experimental Investigation of Surface Roughness and Material Removal Rate in Wire EDM of Stainless Steel 304.

Its unexcelled mechanical and physical properties, in addition to its biocompatibility, have made stainless steel 304 a prime candidate for a wide range of applications. Among different manufacturing techniques, electrical discharge machining (EDM) has shown high potential in processing stainless steel 304 in a controllable manner. This paper reports the results of an experimental investigation into the effect of the process parameters on the obtainable surface roughness and material removal rate of stainless steel 304, when slotted using wire EDM. A full factorial design of the experiment was followed when conducting experimental trials in which the effects of the different levels of the five process parameters; applied voltage, traverse feed, pulse-on time, pulse-off time, and current intensity were investigated. The geometry of the cut slots was characterized using the MATLAB image processing toolbox to detect the edge and precise width of the cut slot along its entire length to determine the material removal rate. In addition, the surface roughness of the side walls of the slots were characterized, and the roughness average was evaluated for the range of the process parameters being examined. The effect of the five process parameters on both responses were studied, and the results revealed that the material removal rate is significantly influenced by feed (p-value = 9.72 × 10-29), followed by current tension (p-value = 6.02 × 10-7), and voltage (p-value = 3.77 × 10-5), while the most significant parameters affecting the surface roughness are current tension (p-value = 1.89 × 10-7), followed by pulse-on time (1.602 × 10-5), and pulse-off time (0.0204). The developed regression models and associated prediction plots offer a reliable tool to predict the effect of the process parameters, and thus enable the optimizing of their effects on both responses; surface roughness and material removal rate. The results also reveal the trade-off between the effect of significant process parameters on the material removal rate and surface roughness. This points out the need for a robust multi-objective optimization technique to identify the process window for obtaining high quality surfaces while keeping the material removal rate as high as possible.

A New CPW-Fed Semicircular Inverted Triangular Shaped Antenna Based on Mixed-Alternate Approach for 5G Millimeter-Wave Wireless Applications.

This paper presents the design and development of a new semicircular inverted triangular shaped antenna for 5G millimeter-wave wireless applications. An alternate-mixed approach based on cavity, slots and loaded stubs is employed in the designed antenna lattice. The suggested antenna structure is formed by a radiator, partial defected metal ground plane and a 50 Ω coplanar waveguide. The proposed antenna resonated at multiple frequencies by the setting up of the proper dimensions and locations of the rectangles, elliptical cut slots and cavity stubs. Furthermore, a parametric analysis is carried out to examine the antenna's effectiveness and impedance-matching controls. The proposed structure is realized on the low-cost RT/Duroid Rogers RO3010™ laminate with an overall small size of 1.381λ0 × 1.08λ0 × 0.098λ0, where λ0 represents the wavelength corresponding to the minimum edge frequency of the 23 GHz at 10 dB impedance bandwidth of the antenna. The antenna's key characteristics in terms of bandwidth, gain, radiation patterns and current distribution have been investigated. The antenna exhibits high performance, including an impedance bandwidth of 19 GHz ranging from 23 GHz to 42 GHz, results in 58.46% wider relative bandwidth calculated at 10 dB scaled return loss, a peak realized gain of 6.75 dBi, optimal radiation efficiency of 89%, stable omnidirectional-shaped radiation patterns and robust current distribution across the antenna structure at multiple resonances. The designed antenna has been fabricated and simulation experiments evaluated its performance. The results demonstrate that the antenna is appropriate and can be well integrated into 5G millimeter-wave wireless communication systems.

Examining the surface roughness and kerf quality of micro-slots cut on the surfaces of Ti-B4C nanocomposites by WEDM: a desirability approach

Micro slots and textures are created on Titanium (Ti) composites to improve its surface characteristics. Micro-textured Ti composites are generally recommended for bio implants, automobile, and aerospace components. In the current research, Ti-B4C nanocomposites were prepared by powder metallurgical route. Micro slots were cut on the Ti-B4C surfaces by Wire Electrical Discharge Machining (WEDM) Technology by varying the current, pulse-ON time, and pulse-OFF time. Scanning electron microscopy and XRD analysis validates the uniform distribution and inclusion of B4C nanoparticles in Ti matrix. Response surface methodology was used to plan the experimental runs. Analysis of variance and desirability analysis were employed to identify the most suitable machining factors for obtaining the minimum surface roughness, lower kerf width and higher material removal rate (MRR). Increase in applied current and pulse-ON time, increases the MRR. Increase of pulse-OFF time from 50 μs to 60 μs gradually reduces the MRR and reduce the surface roughness of the cut slots. Contrastingly an increase in pulse-ON time increases the roughness due to an extensive melting and resolidification of Ti nanocomposites. The morphology of the WEDMed surface reveals the recast layer and localized melting zones on the cut surfaces.

Development of a Wide Bandwidth Massive Eight Dissimilar Radiating Element Multiband MIMO Antenna for mm-Wave Application

This paper proposes a massive MIMO antenna operating on 6GHz frequency as millimeter-wave. It consists of eight dissimilar-shaped radiating elements. The radiating element of the antenna is designed using square shape with different cut slots. Parasitic elements and defected ground structure are introduced for the enhancement of the correlation coefficients and total active reflection coefficients of the MIMO antenna. The rectangular shape parasitic elements are placed between the square radiating patches. The ground plane consists of rectangular shape defected ground structures. The antenna is constructed on the FR-4 substrate. Parameters such as isolation, cross-correlation, and bandwidth are enhanced. The obtained through simulations antenna parameters values of return loss, isolation, cross-correlation, total active reflection coefficients, and bandwidth are less than -10dB, less than -9.30dB, less than 0.16, less than 0.00015, and greater than 200MHz respectively. The antenna operates on various bands with fractional bandwidth greater than 3% for a frequency of 6GHz. This antenna is useful for a variety of applications in wireless systems.

Laser Cut passing‐through Open‐to‐CHS Beam‐to‐Column Connections

AbstractAlthough Circular Hollow Sections (CHS) have always demonstrated their excellent properties in resisting high compression, tension as well as bending in all directions, thanks to their inherent shape and geometry, the existing open ‐to‐CHS connections used in the current industry (conventional connections) generally require a substantial amount of stiffeners or gusset plates due to their construction method i.e. direct welding or diaphragm connections. As a result, huge welding quantities are required which further complicates the fabrication procedure. Furthermore, due to a direct connection, the CHS column becomes prone to localized distortions. In order to minimize the aforementioned drawbacks, a “passing‐through” approach was proposed and investigated in the EU‐RFCS research project LASTEICON where connecting elements (i.e. one or more steel plates or a piece of I‐profile) pass through the CHS column through Laser Cut slots made in the column and the primary beams (namely the “main” I‐beams) are connected to both ends of the passing through elements (named as “through‐members”). The applied shear force, and if relevant the applied moment, is effectively transferred by the “through‐member” to the CHS column, whereas, the CHS column contributes significantly in resisting it through its large flexural and shear capacity. The present article summarizes the most interesting results obtained based on the experimentally validated numerical simulations for the different types of LASTEICON connections. Thanks to the superior fabrication quality and versatility offered by the laser cutting technology, different types of connection configurations were developed within the project. This article introduces a few of these possibilities: (1) Two‐way steel moment resisting connections, (2) Asymmetric steel connections, (3) Four‐way steel connections, and (4) Composite connections.

Analysis of laser cut slots on different thickness steel plates

One of the processes used to separate parts from plate-type workpiece is laser beam cutting. The evaluation of the quality of the machined surfaces can be performed by taking into account the influence exerted by some input factors in the cutting process on the width of the slot and on the roughness of the surfaces generated by the laser beam cutting process. The paper presents the results of experimental research performed on a steel plate type workpiece. The objective pursued was to reveal the influence exerted by several input factors of the laser beam cutting process on some output parameters of this process. Empirical mathematical models corresponding to the output parameters taken into account were established. It was possible to order the input factors in the process by taking into consideration their weight in the values of the output parameters.

Self-diplexing mixed-coupling bandpass filter based on single slotted SIW cavity

A self-diplexing mixed-coupling bandpass filter based on a single slotted substrate-integrated-waveguide (SIW) cavity is proposed. By etching a wide slot, two unequal half-mode SIW parts are constructed and then fed by four coaxial ports to realise two bandpass filters with different centre frequencies. Since this etched slot can serve as a divider and an isolator, a flexible frequency ratio of 0.60–1.66 and high isolation of better than 20.0 dB is achieved. By further cutting the other two narrow slots, four quarter-mode sub-cavities are obtained where the mixed coupling is induced in the pass bands and a transmission zero (TZ) is introduced at the stopbands. The coupling and TZ are controllable by simply adjusting the length of these cut slots, which makes the proposed design easily redesigned for practical applications. A prototype with a size of 0.59λ 0 × 0.59λ 0 × 0.03λ 0 has been fabricated. The measured centre frequency, TZ, 3-dB bandwidth, and insertion loss of the lower pass band is 2.51 GHz, 2.96 GHz, 340 MHz, and 1.67 dB, respectively, whereas those of the upper pass band is 3.06 GHz, 2.53 GHz, 370 MHz, and 2.44 dB, respectively.

Study on Effect of Abrasive Water Jet Machining Process Parameter on Taper Angle during Machining of Epoxy Resin Glass Fibre

Abrasive Water Jet Machining (AWJM) is one of the most advanced machining processes, which has the ability to machine various materials. In this paper, experiment was performed on cutting of epoxy fibre glass by AWJM. Epoxy fibre glass is a composite which consists of fibre glass cloth and epoxy resin as binder, achieved under specific heat and pressure. There are various process parameters such as water pressure, standoff distance, abrasive flow rate, traverse rate, abrasive etc. The water pressure and standoff distance was varied while performing the experiment and rest all parameters were kept constant. From this experiment taper angle was measured and it was observed that taper angle increases as the standoff distance increases, this is because the shape of the jet diverges with larger standoff distance. Minimum taper angle was observed as 0.34° at 32 ksi pressure, having 2 mm standoff distance. It was also observed that width of cut has significant effect on taper angle. From further calculations, the deviation of the cut slot for top width was observed as +1% to 5% and for bottom width it was -1% to 2%.

Characterization of moment resisting I-beam to circular hollow section column connections resorting to passing-through plates

Open-to-Circular Hollow Section (CHS) connections are highly encouraged nowadays in modern multistoried structures due to the extensive resistance provided by the CHS columns against high compression, tension as well as flexure in all directions, combined with their exceptional aesthetics. However, using more and more gusset plates or stiffeners to strengthen a conventional open-to-CHS connection causes economic disadvantage due to excessive welding quantities and substantial CHS chord yielding further limits any opportunity to exploit the full advantages offered by the open sections therefore minimizing its frequent application. However, if designed efficiently, the CHS connection can offer an extensive range of solutions which makes it an impeccable choice for the modern multi-storey structures. To that purpose, a “LASTEICON” solution is proposed in this paper investigating a “passing-through” concept, which is obtained by using laser cutting technology (LCT). Initially, a suitable moment resisting Plate-to-CHS-column connection is characterized through a detailed understanding of the relevant parameters, where the primary beams are connected at either side of the CHS column by two transverse and one longitudinal plate passing through the CHS column via laser cut slots. A detailed parametric study is conducted based on multiple Finite Element (FE) models primarily calibrated from an experimental campaign to understand the effect of each parameter and further verify and therefore establish the analytical assumptions to calculate the ultimate resistance of such connections. Finally a comprehensive design procedure is proposed to design such “passing-through” Plate-to-CHS column connections. A short comparison study is also made with the conventional (direct weld) joints to highlight the advantages offered by this LASTEICON solution.

Влияние кинематической вязкости расплава материалов на качество обработки при тонкоструйной плазменной резке биметаллических композиций

The paper reports the peculiarities in the formation of a cut slot of bimetallic “steel 3 + aluminum 5 M” composition and “steel 3 + copper M1” composition at fine-jet plasma cutting. A different character of a cut channel formation of compositions at a package cut on different sides is revealed. When processing “steel + aluminum” composition on the side of steel a cut surface on the aluminum area has course roughness. A burr formation on the lower edge of a cut is also observed. It is explained by considerable difference in melting temperatures and thermal conduction of steel and aluminum. At the changed of a front side of a cut from steel to aluminum occurs sedimentation of aluminum melt on the steel area which is explained by a high kinematic viscosity of aluminum melt. The formation of refractory oxides in aluminum melt is defined that contributes to the increase of its viscosity and difficulty in the complete elimination from a cut channel. At the cutting of bimetallic “steel 3 + copper M1” composition of a copper side a cut surface on both areas is formed without visible traces of sedimentation of steel and copper melt caused by a low kinematic viscosity of copper and steel melts.

Наукоемкая технология повышения эффективности размерной обработки углепластиков импульсным наносекундным излучением волоконного иттербиевого лазера

In this work there are shown results of the complex theoretical and experimental investigation of laser dimensional treatment of different types of carbon plastics with the thickness of 1mm with the matrix on the base of thermosetting binding agents. In the course of this work fulfillment there was developed an experimental plant on the basis of a pulse nano-second fiber laser of type YLPM-1-4x200-20-20 with the wave length of 1.06 µm and average radiated power of 20 W. The theoretical assessment of a thermal impact area is carried out on a model of an instantaneously operating normally distributed circular source on the surface of a semi-infinite body. In accordance with the assessment given there are formulated recommendations for a choice of definite technological parameters of machining conditions directed to the decrease of a thermal impact area and increase of processing speed. In the course of experimental researches a laser source operated with a maximum average power, beam scanning was carried out by a two-axial galvano-scanner. The experiments were carried out without technological gas supply in are environment at different speeds of beam scanning, laser operating modes, passes number, hatch distances and positions of a focusing plane. The area of a thermal impact and geometry of a cut slot were analyzed with the aid of an optic and electronic microscope and a contour-graph. The work result is recommendations for a choice of technological parameters and an algorithm of processing at which the area of thermal impact is less than 150 µm; taper of a cut slot is less than 100 µm; there are no defects on a surface and a cross profile of the cut slot section; a high speed of processing is achieved.

Improving isolation of slot‐coupled directional couplers

A suitable method is introduced to improve the isolation of slot-coupled directional couplers. The proposed coupler consists of two trapezoidal-shaped patches that are coupled through a trapezoidal-shaped slot in a common ground plane. The inherent phase velocity differences between the even- and odd-modes of the slot-coupled directional coupler are compensated around the centre frequency of the coupler by introducing some slots to the trapezoidal-shaped patches. A design graph is derived by sweeping some dimensions of the coupler. A hatched area is also added to the design graph that indicates the appropriate coupler dimensions which lead to the equal even- and odd-mode phase velocities around the centre frequency. To demonstrate the effectiveness of the proposed coupler, an 8 dB coupler operating from 1 to 3.3 GHz is designed and constructed. The measurement results are in good agreement with the simulation results. The results show that the isolation of the designed coupler has improved significantly in comparison with the other designed coupler with no cut slots in the patches.

Kerf analysis and control in dry micro-wire electrical discharge machining

This paper describes the analysis and control method for the kerf of cut slots in dry micro-wire electrical discharge machining (μ-WEDM). First, the influence of the controllable parameters such as the air injection pressure, relative electrode feedrate, open voltage, and input capacitance were investigated based on the Taguchi methodology. The behavior of the kerf with respect to the workpiece height was also considered. Second, to improve the machining accuracy of the dry μ-WEDM, a control method was developed to compensate for the kerf based on real-time estimation of the material removal rate and by controlling the air injection pressure. In this research, all the experiments were performed in a constant-feedrate mode and with various high-pressure air injection. The experimental results show that the kerf in dry μ-WEDM was significantly affected by the air injection pressure, electrode relative feedrate, and cut height of the workpiece. Moreover, by monitoring the material removal rate of the process, the kerf in dry μ-WEDM was efficiently controlled.

Numerical simulation of rock-burst relief and prevention by water-jet cutting

The applications in coal mine rock burst prevention using water jet cutting technology (WJCT) have progressed slowly. In this paper we analyzed the possibility and reasonableness of WJCT application to rock burst relief and prevention, used the ABAQUS software to simulate the distributive characteristics of stress and energy fields suffered by hard coal roadway wallrock and the internal relationships of the fields to the instability due to WJC on roadway wallrock, and conducted field WJCT tests using electromagnetic radiation (EMR) measurement technology. The results showed that WJCT can unload rock burst effectively by inducing stress release and energy dissipation in coal mass near its cut slots; its annular slots also can decrease rock burst risks through blocking or weakening stress and energy transfer in coal mass. The horizontal radial slots and annular vertical slots may cause “the beam structure” and “the small pillar skeleton”, and “the layered energy reservoir structure”, respectively, which lead to an increase in stress concentration and energy accumulation in coal element mass near the slots. The reasonable design and optimization of slots׳ positions and their combination not only can significantly reduce the scope of stress concentration and energy accumulation, but also can destroy coal mass structure on a larger scale to force stress to transfer deeper coal mass, eventually avoiding high intensity and large-scale rock bursts. The field tests of WJC for pressure relief using EMR verified the above conclusions.

Planar Finger-Shaped Antenna used in Ultra-Wideband Wireless Systems

Recently, extensive requirements have developed for ultra-wideband (UWB) technology that provides high activity and small size for use in small communication systems, remote sensing, and radar applications. Thus, we concentrated with high-resolution radar UWB antenna to cover Federal Communication Commission’s (FCC) standard UWB range (3.1-10.6 GHz). The proposed ideal-size and low-cost finger-shaped patch antenna of 24 mm x 19 mm printed on 40 mm x 35 mm rectangular Taconic TLY-5 material was designed and established through experiments and simulations. Results show that the two cut notches of 1.5 mm x 2 mm at the bottom corners of the patch can increase the bandwidth. To increase the radiation area and achieve more resonance frequencies, two cut slots at the top edge of the patch were designed in depth of 10 mm. Four parameters were considered in the analysis of the proposed antenna design, namely the feeder width, number of slots, number of notches, and feed gap space. The simulated and measured results of the main antenna parameters make the design suitable in applications of UWB wireless systems.