A. Mathematical Model of the Circuit in the AC Side Assuming that the PFC technique is properly applied to the proposed converter and that the circuit operates under continuous conduction mode (CCM), there are eight switching states of the six bidirectional switches, which are summarized in Table I, in which three auxiliary variables γ1, γ2, and γ3 are used to determine the connection between the three input lines and the voltage multiplier. Two equivalent circuits corresponding to two of the eight switching states are shown in Fig. 3.2, and the other six can be easily obtained. It has to be noted that, in Fig. 3.2, vγ represents the terminal voltage of the CWVM, whose value is determined by the combination of the capacitor voltage(s) of the CWVM according to diode-conducting states. Consequently, the ac-side mathematical model of the proposed converter is given as
The crystal growth process chosen can ensure high quality crystallinity in the lithium niobate. Low-loss thin films of lithium niobate have been sputtered onto alternative substrates including sapphire and silica . Liquid phase epitaxial growth on patterned substrates also offers flexible options for fabricating waveguides [24, 25]. Here we report liquid phase epitaxy growth of channel waveguides on laser-machined substrates to fabricate high optical quality lithium niobate channel waveguides with single crystalline properties on lithium niobate and lithium tantalate substrates. Liquid phase epitaxy is a versatile crystal growth technique which creates a step-index profile rather than a graded-index profile for improved mode confinement. A slight dissolution at the surface during the process leads to smoothing of the waveguide edges, thus reducing the losses. Furthermore, by using lithium tantalate substrates, high refractive index contrast can be realized for both optical polarization directions.
Diﬀerential phase shifters are commonly employed in wideband phase-array antennas, mobile satellite systems and measuring instruments, etc. Schiﬀman  introduced a phase shifter which has a main line built around a shorted coupled line and a simple transmission line serves as the reference line. However, it was based on a strip line that for speciﬁc bandwidth requirement, often necessitated very tight coupling. Various improvements over the Schiﬀman phase shifter using cascade and parallel combination of shorted coupled line have been introduced [2–4], but again, tight coupling is still required. The implementation of a phase shifter using selectively etching the underneath of the coupled lines and placing a material of diﬀerent permittivity to change the even and odd mode impedance values is an interesting idea . A return loss better than 10 dB and a bandwidth up to 70% have been achieved by doing so, but this phase shifter requires extra process step. Phase shifters reported in [6, 7] provide wide bandwidth but these designs also require multilayer fabrication process which increases their fabrication cost and may not be compatible with other part of the circuit. A design using stub loaded line reported in  has relatively smaller insertion loss and could provide a bandwidth up to 82%. Some other interesting designs have been reported in literature as well [9–12] and their performance are given at the end of this paper in the comparison section; majority of them rely on multilayer processing. A technique to utilize single reference line and multiple main lines to achieve diﬀerent phase shifts was reported in , and can provide 45% bandwidth with a phase deviation of 5 ◦ and with an insertion loss up to 0.9 dB. While in  the main line is formed by changing the position of the stubs and could attain a bandwidth of 55.6% with a return loss up to 0.7 dB considering a phase deviation of 8 ◦ , the multilayer technique reported in  achieves a bandwidth of 112%. A modiﬁed version of the Shiﬀman phase shifter with the reference line also comprising of a coupled line was reported in , while  is limited to providing only 180 ◦ phase shift.
The chitosan and HA/chitosan composite scaffolds were suc- cessfully fabricated using thermally induced phase separation technique. By varying the materials and processing parame- ters, degree of porosity and pore sizes of the scaffolds could be modulated. The scaffolds were highly porous and exhibited interconnected porous structure with pore sizes from 20 𝜇m to 350 𝜇m. HA nanoparticles were successfully incorporated which reduced the initial water uptake properties of the scaffolds and also enhanced compressive mechanical proper- ties. Biodegradable and biocompatible porous scaffolds were demonstrated to be suitable for in vitro cell culture and are expected to allow cell attachment and tissue in-growth when used in vivo.
The output of rectifier will not be sufficient for the inverter to give the output of line to line voltage 415V AC. So a boost converter is designed and kept in between rectifier and inverter circuit which will boost the DC value from 300V to 600V, as then boost converter circuit is connected to six leg inverter which consists of IGBTs to convert to three phase AC. Each gate of IGBT is connected to of microcontroller. In microcontroller the embedded program of sine PWM is loaded and which drives the IGBT .
This paper presents a design of a step-down transformer for supplying electrical power of output 10KVA, 250V and operating at a frequency of 50Hz. A precise calculation is made in designing the transformer such as window size, core area, thickness of yoke, number of turns and wire thickness of LT winding and HT winding, efficiency and overall transformer size such as length, width and height. The accurate calculation will give more efficiency of the transformer. High efficiency transformer is needed for good performance and to avoid the power loss. Power loss is high in low efficiency transformer.
Then, the net effect of the clock CLK to series to connected MN1 and MN3 is equivalent to applying a locally generated pulse to the circuit. By adding the NAND gate in Figure 3(a), the circuit allows the reduction of the pulse window by about one inverter delay at the expense of a small space penalty for increased loading on node ‘X’. The operating principle of the SDDFF is described briefly as follows. When the clock signal is at falling edge, the flip-flop is going to pre-charge phase. Node ‘X’ is pre charged to supply voltage Vdd at that time output node ‘Q’ is cutting off from input stage. So, the output static latch holds previous value. When the clock is at rising edge, the flip-flop enters into evaluation phase. The evaluation phase begins with the rising edge of clock CLK. If input D is low the flip-flop is latching a zero, node ‘X’ will remain high. In this situation the output node ‘Q’ either will remain low or will be discharged through transistors MN4-MN5. If input D were high prior to evaluation phase the flip-flop is latching one node ‘X’ would be discharged through the pull down path MN1- MN3. The falling transition of ‘X’ would turn transistor MP2 ON, driving output ‘Q’ high.
The microstructures of the specimens after solution treatment were studied by using different cooling rates to reduce the temperature from solid solution to room temperature. When the cooling rate is low, most of the precipitates have undergone relatively full free growth. After a long cooling process, the precipitation phases eventually come close to each other in four groups to form butterfly- like structure knots. The volume of the phase is large and the cube structure with sharp edges and corners is tetragonal in cross section, and the channel of the matrix phase is relatively wide. When the cooling rate increases, the number of phases increases, the volume of the final phase decreases, and the curvature of the corner decreases, and the channel of the matrix phase becomes finer. When air cooling is used, the precipitation phases in the material show irregular spheres, and the volume of the phase decreases obviously compared with the cooling rate at 0.15°C. From the cross section, the phase is irregular circular, a few have the tendency of edge angle, and the channel of the matrix phase is finer, and there are fine secondary precipitation phases precipitated. When the cooling rate is faster than that of water cooling, it is difficult to see the microstructure of the structure under the existing micro-electron microscopy. It can be seen that the micro-spheres are piled up in disorder. Because of the rapid cooling rate, the precipitation phase ends growing and solidifies in a very short time after precipitation.
general, however, a filter’s gain may be specified at several different frequencies, or over a band of frequencies. Since filters are defined by their frequency-domain effects on signals, it makes sense that the most useful analytical and graphical descriptions of filters also fall into the frequency domain. Thus, curves of gain vs frequency and phase vs frequency are commonly used to illustrate filter characteristics, and the most widely-used mathematical tools are based in the frequency domain.
Compared to the standard L297 the difference are the addition of a pulse doubler on the step clock input and the availability of the output of the direction flip flop (block diagram, figure 20). To add these functions while keeping the low-cost 20-pin package the CONTROL and SYNC pins are not available on this version (they are note needed anyway). The chopper acts on the ABCD phase lines.
Abstract: Software defined radio (SDR) is the future trend for mobile communication. A SDR is supposed to facilitate high speed multimedia application for future mobile standards. Adaptive modulation forms an integral part of SDR system with robust and high data rate capability. Here we have analyzed adaptive modulation scheme with their performance in changing channel condition. The modulation scheme studied for adaptive modulation are BPSK, QPSK 16QAM , 32 QAM ,64 QAM . Different order modulations and different coding schemes, allow to send more bits per symbol, thus gaining higher throughputs and better spectral efficiencies. But it must also be noted that when using a modulation technique such as 64-QAM with less overhead bits, better signal-to-noise ratios (SNRs) are necessary to overcome any Intersymbol Interference (ISI) and also maintain a certain bit error ratio (BER). The use of adaptive modulation gains wireless technologies to yielding higher throughputs while also covering long distances. This paper focusing on the physical layer design (i.e. Modulation), here the various used modulation type will be implemented in a single Matlab function that can be called with the appropriate coefficients. A comparison will be made in terms of SNR and BER relation.
In present years, microcontrollers, Digital Signal Processors (DSPs), DSP IC been widely used implementing control motor algorithms in industry. But it has some disadvantages like, long development period and poor software portability and re-usability. Any changes in the program, imposed in the introduction to the need of good performance or new features require a large change to the project, to fit with the new system. To satisfy these demands a FPGA based hardware implementation technology is used. For three phase induction motor speed control, AC motor drives Pulse Width Modulation (PWM) inverters used in drive applications. Both the magnitude and frequency of the applied voltage to a motor can be controlled by PWM inverters.
hydrotermal, microwave techniques, CVD, sputtering, sonochemical and mechanochemical . For the synthesis of SnO nanostructure, different methods have been reported, such as hydrothermal , sonochemical , combustion , co-precipitation , gas phase condensation , ionthermal  and sputtering . In most of these methods, the final products are multi- phase with structures of nanowhiskers, flowerlike, nanodiskettes, nano plates, nano robs, etc [7-12].
Both physicists and chemists are interested in effective and reproducible methods to prepare single atoms; but whereas the former scientists will use advanced technology such as that required to bring atoms to ultralow temperatures of 170 nanokelvin (170 billionth of a degree above absolute zero) and to extract the information from the experimental observables, chemists are interested in developing scalable methods to support single atoms to be used as main components of newly prepared catalysts for the synthesis of known and still unknown substances, namely the main objective and the greatest success of chemistry.
The equivalence of coherence and indistinguishability is an very important result in the perspective of wave-particle duality. Coherence is one of the main criteria for interference of light beams. On the other hand in single photon interference experiment the lack of photon’s path information plays a crucial role. In his famous article L. Mandel 1 has shown that the
AlFeSi phase, improve their morphology and distribution. In addition, some scholars  believe that the temperature range of some alloy phases is changed because the RE La is easily accumulated in the front edge of solid-liquid interface when 6063 alloy is added with a small amount of RE La. For one thing, it causes the decrease of solidification temperature, the increase of growth speed and the decrease of dendrite spacing. For another thing, it causes the redistribution of solute at the front of solid-liquid interface during dendrite growth, which results in the increase of super-cooled zone of composition, the increase of crystal core and the decrease of dendrite spacing.
Abstract: As novel materials for carbon capture, phase change solvents can separate into two immiscible phases during the CO2 capturing procedure under a certain temperature. The solvent systems can significantly decrease the energy consumption since the solvents can be regenerated by only heating the rich-CO2 phase. In this work, amino acid ionic liquids (AAILs) were synthesized using quaternary ammonium salts and amino acids as raw materials, and the aqueous solutions were prepared as novel liquid-solid phase change solvents. The results showed that the solvents had excellent CO2 absorption capacity, and the AAILs functionalized by glycine and tryptophan exhibited significant phase change properties. The mechanism of phase-change of the solvent were mainly due to the lower solubility of the product after reaction between AAILs and CO2. The solvent with tryptophan as anion could be regenerated by only heating the CO2-riched solid phase, which might significantly decrease energy consumption of regeneration. And the absorbent could be reused with the regenerated absorption ratio up to 79%. The solvent system has great potential in industrial application due to the easy operation process and efficient recycling ability.