Total Input Power Research Articles

Evaluation of the turbulent kinetic dissipation rate in an agitated vessel

The design of agitated tanks depends on operating conditions and processes for that are used for. An important parameter for the scale-up modelling is the dissipation rate of the turbulent kinetic energy. The dissipation rate is commonly assumed to be a function of the impeller power input. But this approach gives no information about distribution of the dissipation rate inside the agitated volume. In this paper the distributions of the dissipation rate inside the agitated vessels are estimated by evaluations of the CFD (Computational Fluid Dynamics). The results obtained from RANS (Reynolds Averaged Navier-Stokes equations) k-e turbulent model and LES (Large Eddy Simulations) with Smagorinsky SGS (Sub Grid Scale) model are compared. The agitated vessels with standard geometry equipped with four baffles and stirred by either a standard Rushton turbine or a high shear impeller were investigated. The results are compared with mean dissipation rate estimated from the total impeller power input.

Optimization of multi-slot coaxial antennas for microwave thermotherapy based on the S11-parameter analysis

The underlying aim of presented article is to determine the optimal location and sizes of the air gaps inside a multi-slot coaxial antenna with 50-ohm feed based on the S11-parameter characteristics of microwave applicator to get the best antenna impedance matching to the treated tissue. The next step is the selection of the limit levels of the antenna input power, for which temperature of the tissue do not exceed known therapeutic elevations for microwave therapies at hyperthermic and ablation temperatures. The proposed approach provides a relatively simple method for optimization of the location and size of slots in the antenna structure. The proper choice of limit values of total antenna input power enables appropriate adjustment of temperature of the target tissue to preserve optimal cancer treatment.

Asymmetrical Dead-Time Control Driver for Buck Regulator

This brief presents an asymmetrical dead-time control driver (ASDTCD) for synchronous buck converter operating in the continuous conduction mode. Dead-time control is an important metric for improving the efficiency of switching mode power regulator. Without an additional circuit, the proposed ASDTCD can generate dead time by controlling the slope for the output signal of the driver. The proposed ASDTCD utilizes the transition between triode region and saturation region for the power transistor to avoid body-diode conduction and shoot-through current while minimizing the switching loss. Thus, high-speed body-diode conduction sensor is avoided; thereby, reducing the power consumption and saving silicon area. In addition, the body-diode conduction time control accuracy is also enhanced. Less than 1-ns body-diode conduction time has been achieved without bringing in shoot-through current across 10–450-mA load range. With less than 0.5% of the total input power consumed, the proposed ASDTCD takes less than 1% of the power transistor area. This design is implemented in the 0.18- $\mu \text{m}$ CMOS process.

Electron heating and particle fluxes in dual frequency atmospheric-pressure helium capacitive discharge

In this letter, a 1D fluid model has been used to study the electron heating and particle transport in dual frequency atmospheric-pressure helium capacitive discharge with a high-frequency (HF) voltage of 10 MHz and a low-frequency (LF) voltage of 1 MHz. The electric field is decoupled to three components: the HF, the LF and the direct current (DC) ones, and they have much different effects on the plasmas. The eletrons in plasma bulk are mainly heated by the HF electric field, while in plasma sheath they are heated and cooled by the LF and DC electric fields, respectively. With a fixed total input power, the increase of LF power leads to great enhancement of the electrode fluxes of electrons and ions, especially for the energetic electrons of Te > 2 eV, because more power is dissipated in the vicinity of electrodes and the inelastic collision is more pronounced. Therefore, the particle transport on the treated sample can be greatly enhanced without additional gas heating in dual frequency plasmas, which meets the application requirements more compared to the single frequency plasmas.

Microwave Plasma-Activated Chemical Vapor Deposition of Nitrogen-Doped Diamond. II: CH4/N2/H2 Plasmas.

We report a combined experimental and modeling study of microwave-activated dilute CH4/N2/H2 plasmas, as used for chemical vapor deposition (CVD) of diamond, under very similar conditions to previous studies of CH4/H2, CH4/H2/Ar, and N2/H2 gas mixtures. Using cavity ring-down spectroscopy, absolute column densities of CH(X, v = 0), CN(X, v = 0), and NH(X, v = 0) radicals in the hot plasma have been determined as functions of height, z, source gas mixing ratio, total gas pressure, p, and input power, P. Optical emission spectroscopy has been used to investigate, with respect to the same variables, the relative number densities of electronically excited species, namely, H atoms, CH, C2, CN, and NH radicals and triplet N2 molecules. The measurements have been reproduced and rationalized from first-principles by 2-D (r, z) coupled kinetic and transport modeling, and comparison between experiment and simulation has afforded a detailed understanding of C/N/H plasma-chemical reactivity and variations with process conditions and with location within the reactor. The experimentally validated simulations have been extended to much lower N2 input fractions and higher microwave powers than were probed experimentally, providing predictions for the gas-phase chemistry adjacent to the diamond surface and its variation across a wide range of conditions employed in practical diamond-growing CVD processes. The strongly bound N2 molecule is very resistant to dissociation at the input MW powers and pressures prevailing in typical diamond CVD reactors, but its chemical reactivity is boosted through energy pooling in its lowest-lying (metastable) triplet state and subsequent reactions with H atoms. For a CH4 input mole fraction of 4%, with N2 present at 1–6000 ppm, at pressure p = 150 Torr, and with applied microwave power P = 1.5 kW, the near-substrate gas-phase N atom concentration, [N]ns, scales linearly with the N2 input mole fraction and exceeds the concentrations [NH]ns, [NH2]ns, and [CN]ns of other reactive nitrogen-containing species by up to an order of magnitude. The ratio [N]ns/[CH3]ns scales proportionally with (but is 102–103 times smaller than) the ratio of the N2 to CH4 input mole fractions for the given values of p and P, but [N]ns/[CN]ns decreases (and thus the potential importance of CN in contributing to N-doped diamond growth increases) as p and P increase. Possible insights regarding the well-documented effects of trace N2 additions on the growth rates and morphologies of diamond films formed by CVD using MW-activated CH4/H2 gas mixtures are briefly considered.

Gain variation induced by power transient in thulium-doped fiber amplifier at 2 µm and its reduction by optical gain clamping technique

This paper investigates the dynamic behavior of a thulium doped fiber amplifier (TDFA) operating in the 2µm region for reconfigurable wavelength division multiplexing (WDM) systems. We show deleterious channel power fluctuations may be generated by input power variation at the amplifier and we propose the use of an optical gain-clamping technique. The investigated system consists of 20 channels with −4dBm total input power. Our findings revealed that the effects of power transients due to channel reconfigurations are significantly reduced by a lasing feedback signal. Simulation results show that a power excursion of 4.3dB is produced after dropping 19 channels when the amplifier gain is unclamped and only 0.0062dB when the amplifier gain is clamped. The dynamics of GC-TDFA are mainly influenced by the value of the pump power factor and thus the laser signal achieves a stronger stabilization condition with increasing pump power factor. Hence, optical gain clamping is a simple and robust technique to control the power transient in the thulium-doped fiber amplifier of WDM systems at 2µm.

Composition and mechanical properties of B-C-W and B-C-Ti thin films prepared by pulse magnetron sputtering

In the present work, coatings in the material systems B-C-W and B-C-Ti have been synthesized by pulse magnetron sputtering, to exploit their potential as coatings for hard, wear resistant applications. These layers offer interesting properties, because of the possible amounts of carbides and borides that can form in the non-equilibrium deposition processes. Especially the amount of tungsten in the layers promises high wear resistance and corrosion protection at elevated temperatures.The B-C-W and B-C-Ti thin films have been deposited by pulsed magnetron co-sputtering in bipolar mode, using a boron carbide (B4C) target and a metal target (W or Ti) with a maximum total power input of 12.9W/cm2. The amount of metal in the layers has been varied by adjusting the sputtering pulse length of the respective target material. The influence of bias voltage on the properties of B-C-W coatings has been investigated and it was found out that bias voltages of −60V … −100V lower the hardness of the coatings.The hardness and the Young's modulus of the layers have been determined by nanoindentation. Whereas the majority of coatings exhibits hardness around 20GPa or lower, maximum hardness of 28GPa and Young's modulus of 420GPa are observed in a certain compositional range, in which coatings also distinguish by good thermal stability. Their composition has been analysed by using optical glow discharge emission spectroscopy (GD-OES) and Rutherford backscattering spectrometry (RBS).

All-optical Phase Regeneration with Record PSA Extinction Ratio in a Low-birefringence Silicon Germanium Waveguide

We report a low-power continuous wave-pumped phase sensitive amplifier (PSA)-based phase regenerator implemented in a passive silicon-based waveguide. A polarization assisted-PSA, consisting of two orthogonally-polarized pumps and a phase-locked signal copolarized to one of them, was implemented in a low-birefringence silicon germanium (SiGe) waveguide. The strong TE/TM modal symmetry of the waveguide and its large nonlinear coefficient enabled the achievement of an extremely large phase sensitive extinction ratio of approximately 29 dB for a total input power of only 21.3 dBm. This SiGe-based PSA was used to demonstrate phase regeneration on a 20 Gb/s differential phase-shift keying signal, thereby reducing its error vector magnitude and phase error by three and six times respectively and enabling a bit-error ratio improvement of up to 2 dB.

Environmentally friendly electrochemical recycling of indium from scrap ITO glass and PET

Indium, the key raw material used in liquid crystal displays (LCDs), light-emitting diodes (LEDs), and solar cells, is a rare metal. The demand for devices that use touch panels has grown enormously, and Indium has become a vital and indispensible material. However, the worldwide depletion of indium resources has made it necessary to recycle as much indium as possible. This is done not only for commercial purposes but also to protect the environment. Although direct electrochemical methods can be used to remove the indium-tin oxide (ITO) layer from intact discarded or defective thin-film transistor (TFT)-LCDs or from flexible polyethylene terephthalate (PET) touch panels, it is not possible to do this with broken or cracked panels, large numbers of glass fragments, or deformed PET material because the necessary electrical connections cannot be made. Therefore, in this study, an indirect electric discharge process was used. Tests were made using DC straight polarity and DC reverse polarity, and a multicylinder electrode was used to conduct carrying out of positive (or negative) electrical discharge in the electrode assembly without the need for electrical connection to the workpiece. An electric field is created by electrical discharge between the cathode and anode through the electrolyte to create an electrical field between the electrode and the ITO surfaces. There is no likelihood of the electrodes making direct contact with the ITO glass fragments, and so, the danger of short circuits is avoided. This method facilitates the smooth and highly efficient recycling of indium avoiding methods that use strong acids and other chemicals that are harmful to the environment. The higher the current used, the faster the feed rate of the workpiece can be, and removal will also be more efficient. A small gap between the electrodes (1 mm) will also speed up the removal rate. Pulsed DC current is conducive to the rapid removal of deposits of electrochemical by-product and also allows a higher feed rate. However, this raises the total electrical power input. The use of ultrasonics speeds up ITO removal as does an increase in electrolyte temperature. A small-diameter anode and a small gap between the electrodes also speed up the removal rate.

Design of novel dual-port tapered waveguide plasma apparatus by numerical analysis

Microwave plasma apparatus is often of particular interest due to their superiority of low cost, electrode contamination free, and suitability for industrial production. However, there exist problems of unstable plasma and low electron density in conventional waveguide apparatus based on single port, due to low strength and non-uniformity of microwave field. This study proposes a novel dual-port tapered waveguide plasma apparatus based on power-combining technique, to improve the strength and uniformity of microwave field for the applications of plasma. A 3D model of microwave-induced plasma (field frequency 2.45 GHz) in argon at atmospheric pressure is presented. On the condition that the total input power is 500 W, simulations indicate that coherent power-combining will maximize the electric-field strength to 3.32 × 105 V/m and improve the uniformity of distributed microwave field, which raised 36.7% and 47.2%, respectively, compared to conventional waveguide apparatus of single port. To study the optimum conditions for industrial application, a 2D argon fluid model based on above structure is presented. It demonstrates that relatively uniform and high-density plasma is obtained at an argon flow rate of 200 ml/min. The contrastive result of electric-field distribution, electron density, and gas temperature is also valid and clearly proves the superiority of coherent power-combining to conventional technique in flow field.

직류 마이크로 할로우 음극 방전을 이용한 이단 마이크로 플라즈마 추력기의 배기 플룸의 형상 특성

이단 마이크로 할로우 음극 방전(MHCD) 플라즈마를 사용하는 마이크로 플라즈마 추력기(<TEX>${\mu}PT$</TEX>)에 대한 실험 연구가 수행되었다. 40 sccm의 아르곤 유량과 10 W 미만의 전력으로 보다 더 직진성 있고 긴 침투 길이를 가진 배기 플룸을 만드는 정전기적 가속이 이단 MHCD에 의해 발생되었다. 전압-전류 특성에서는 이단 운전 시 두 번째 단의 가속 전압이 일정하게 되는 최적 영역이 있음을 보였다. 추정된 배기 플룸의 길이가 가속 전압으로 추산된 이론적 배출 속도와 비슷한 증가 경향을 보였다. 다중 채널을 가진 마이크로 플라즈마 추력기는 동일한 총 전력량에 대하여 단일 채널 추력기와 비슷한 특성을 보여, 이는 채널 당 허용 전력량을 낮춰 전체 전력량을 높일 수 있음을 의미한다. 아르곤 원자 분광선의 볼츠만 그래프에서 배기 플룸의 평균 전자 여기 온도는 약 2.6 eV(=약 30,170 K)임이 확인되었다. Micro plasma thruster (<TEX>${\mu}PT$</TEX>) was studied experimentally with a dual-stage micro-hollow cathode discharge (MHCD) plasma. Electrostatic-like acceleration exhibiting more directional and elongated exhaust plume was achieved by a dual layer MHCD at the total input power less than 10 W with argon flow rate of 40 sccm. V-I characteristic indicated that there was an optimal regime for dual-stage operation where the acceleration voltage across the second stage remained constant. Estimated exhaust plume length showed a similar trend to the analytic estimate of exhaust velocity which scales with an acceleration voltage. <TEX>${\mu}PT$</TEX> with multiple holes exhibited similar performance with single-hole thruster indicating that higher power loading is possible owing to decreased power through each hole. Boltzmann plot of atomic argon spectral lines showed average electron excitation temperature of about 2.6 eV (~30,170 K) in the exhaust plume.

Mooring observations of the near-inertial wave wake of Hurricane Ida (2009)

The near-inertial wave wake of Hurricane Ida is examined of the basis of horizontal velocity observations acquired from 7 moorings instrumented with acoustic Doppler current profilers deployed across the shelf break, slope, and at the abyssal plain of the Yucatan Peninsula, from 130m to ∼3300m. During the forced stage, background mean-flow consisted on a dominant cyclonic circulation of ∼100km of diameter intensified toward the Yucatan's shelf (topographic constraint) and bounded by anticyclonic vorticity northeastward (north 25°N). In the low frequency band, subinertial signals of ∈[5.5–7.5]day period propagating along the Yucatan shelf break. After the passage of Hurricane Ida, energetic near-inertial oscillations spread away from the storm's track over cyclonic vorticity. The wave's Eulerian frequency increases shoreward and toward the Yucatan's shelf. After Ida's passage, mooring data show a contrasting velocity response: semi-diurnal and diurnal tides are enhanced at the shelf break of the Yucatan Peninsula and near-inertial oscillations at the slope and abyssal plain. The near-inertial kinetic energy is largest to the right of the storm track because of the asymmetric wind-stress and amplified due to vorticity trapping near z=−500m, which is a proxy of the base of the mesoscale structure and where the mean-flow is nearly zero. The blue frequency shifted wave wake propagates downward at ∼57–70mday−1 and horizontally at 23–28kmday−1 leading a downward vertical energy flux of [1.3–1.6]×10−2Wm−2. This represents a 7–9% of the total wind power input to near-inertial oscillations that, ultimately, became available for interior ocean mixing. The results suggest that the most energetic wave packet propagated poleward and downward from a broad upwelling region located near the Hurricane's track. The vertical structure of the near-inertial kinetic energy is described as a sum of the first 12 standing vertical modes and as vertically propagating near-inertial internal waves. The amplification of near-inertial kinetic energy as the wave train propagates through the region of anticyclonic vorticity is consistent with the reduction of the Eulerian frequency (and mean-flow) at depth and the shrinking horizontal wavenumber in a critical layer. This work shows that energetic near-inertial oscillations of vertical wavelength of 850–1280m, penetrate well below the thermocline, and are concentrated to the right of the storm track in a region of anticyclonic vorticity.

The ride comfort and energy-regenerative characteristics analysis of hydraulic-electricity energy regenerative suspension

For optimization of performances of a hydraulic-electricity energy regenerative suspension (HERS) unit, the tradeoff point was determined based on study of ride comfort and energy-regenerative characteristics of a HERS unit in this study. A HERS unit as a new energy reclaiming suspension device is equipped with an energy-harvesting hydraulic electromagnetic shock absorber (HESA). The HESA together with a quarter car was modeled based on theoretical analysis and experiments, in which the root mean square (RMS) values of the sprung mass vibration acceleration and the recovered power are regarded as the optimization objectives under different road excitation conditions such as the constraints (natural frequency, dynamic displacement, and dynamic load of wheels). The HERS unit was optimized after the relationship between the ride comfort and the energy regeneration was obtained. In comparison with the traditional suspension, the HERS unit may be utilized to improve the ride comfort and meet the vehicle-driving requirements. Moreover, the total input power may be saved by 34-100 W on average while the vibration acceleration is among 0.65-1.06 m/s2. Furthermore, it is verified that the HERS damping force control is the feasible under various load currents.

The role of carbon and nitrogen on the H-mode confinement in ASDEX Upgrade with a metal wall

Carbon (CD4) and nitrogen (N2) have been seeded in ASDEX Upgrade (AUG) with a tungsten wall and have both led to a 20–30% confinement improvement. The reference plasma is a standard target plasma with Ip /BT = 1 MA/2.5 T, total input power Ptot ~ 12 MW and normalized pressure of βN ~ 1.8. Carbon and nitrogen are almost perfectly exchangeable for the core, pedestal and divertor plasma in this experiment where impurity concentrations of C and N of 2% are achieved and Zeff only mildly increases from ~1.3 to ~1.7. As the radiation potentials of C and N are similar and peak well below 100 eV, both impurities act as divertor radiators and radiate well outside the pedestal region. The outer divertor is purposely kept in an attached state when C and N are seeded to avoid confinement degradation by detachment. As reported in earlier publications for nitrogen, carbon is also seen to reduce the high field side high density (the so-called HFSHD) in the scrape off layer above the inner divertor strike point by about 50%. This is accompanied by a confinement improvement for both low (δ ~ 0.25) and high (δ ~ 0.4) triangularity configurations for both seeding gases, due to an increase of pedestal temperature and stiff core temperature profiles. The electron density profiles show no apparent change due to the seeding. As an orthogonal effect, increasing the triangularity leads to an additionally increased pedestal density, independent of the impurity seeding. This experiment further closes the gap in understanding the confinement differences observed in carbon and metal wall devices; the absence of carbon can be substituted by nitrogen which leads to a similar confinement benefit. So far, no definite physics explanation for the confinement enhancement has been obtained, but the experimental observations in this paper provide input for further model development.

Hybrid Design and Performance Tests of a Hovering Insect-inspired Flapping-wing Micro Aerial Vehicle

Hovering ability is one of the most desired features in Flapping-Wing Micro Air Vehicles (FW-MAVs). This paper presents a hybrid design of flapping wing and fixed wing, which combines two flapping wings and two fixed wings to take advantage of the double wing clap-and-fling effect for high thrust production, and utilizes the fixed wings as the stabilizing surfaces for inherently stable hovering flight. Force measurement shows that the effect of wing clap-and-fling significantly enhances the cycle-averaged vertical thrust up to 44.82% at 12.4 Hz. The effect of ventral wing clap-and-fling due to presence of fixed wings produces about 11% increase of thrust-to-power ratio, and the insect-inspired FW-MAV can produce enough cycle-averaged vertical thrust of 14.76 g for lift-off at 10 Hz, and 24 g at maximum frequency of 12.4 Hz. Power measurement indicates that the power consumed for aerodynamic forces and wing inertia, and power loss due to gearbox friction and mechanism inertia was about 80% and 20% of the total input power, respectively. The proposed insect-inspired FW-MAV could endure three-minute flight, and demonstrate a good flight performance in terms of vertical take-off, hovering, and control with an onboard 3.7 V-70 mAh LiPo battery and control system.

Non-resonant piezoelectric transformer based power converter for ultra-low-power electronic devices

Piezoelectric transformer is used in its resonance frequency range to step-up or -down the input voltage. When the transformer is operated with alternating voltage in the non-resonance frequency range, which can be a few hertz, the transformer input works as an actuator, and the isolated output as a sensor to step-down the voltage. The output voltage has a linear relationship to its input the voltage. In this paper, the piezoelectric transformer in the non-resonant and low frequency range is represented by an equivalent circuit. A power converter that steps-down the mains voltage of 220V and 60Hz to supply power to a micro-watt consuming wireless sensor node is presented. This small size, fewer component, isolated, low EMI, and no inductive component converter has total input power consumption of 31mW with 3V and 11.2μW of output voltage and power respectively.

An exact solution for the calendering analysis of a third-order fluid

This paper presents the exact solution for calendering a third-order fluid under lubrication approximation. The solution obtained is valid for all values of the third-order fluid parameter. This exact solution is compared to the perturbation solution. The results show that the perturbation solution is valid for very small values of the third-order fluid parameter. Therefore, no significant deviation from the corresponding results of the Newtonian fluid is observed with the perturbation solution. The interesting quantities for mechanically designing a calendering system such as the force separating the two rolls and total power input into both rolls are calculated and shown graphically for large third-order fluid parameter. The material’s rheological features modify the pressure, flow characteristics, and all other operating variables significantly. In fact, the nip region pressure increases with increasing third-order fluid parameter. The exiting sheet thickness, power input, and roll separating force also increase with increasing third-order fluid parameter.

Anode Geometry Effects on Ion Beam Energy Performance in Helicon Electrostatic Thruster

The ion beam energy performance in a helicon electrostatic thruster with various anode geometries was investigated. For discharge voltages from 100 to 300 V, the ion beam energy increased almost linearly with the discharge voltage. The rate of increase strongly depended on the anode inner diameter (ID). However, the ion beam energy was fit to a single linear function of the total input power irrespective of the anode ID. The effect of an insulation cover set on the side wall of the anode depended on the anode ID; while with the anode ID being equaled to that of the helicon source tube, i.e., 27 mm, the ion beam energy was decreased by about 30%, with the anode ID of 40 mm the electrostatic acceleration became negligible. Under typical operation conditions, the ion beam energy had a flat-hat profile with a diverging angle of 47°; the specific impulse, thrust efficiency, and propellant utilization efficiency evaluated from probe survey measurements were 2000 s, 9.7%, and 98%, respectively.

Neural Network Based Control for Power Quality Improvement and Voltage Regulation in Multi Output Switched Mode Power Supply

Medical electronic equipments and personal computers stand in need of switched mode power supplies (SMPS) with isolated and regulated voltages of ± 12V, ± 5V and + 3.3 V. In this paper a neural network controlled forward boost converter based SMPS of 175 W rating is proposed. The SMPS is designed to have isolated and regulated voltages of ± 12V and ± 5V suitable for PC power supply. Power quality in terms of, total harmonic distortion (THD) and input power factor and output voltage regulation are analyzed for variation in supply voltage and load conditions by simulating the proposed circuit in MAT LAB/Simulink software. To highlight the performance of the proposed multi output SMPS, it is compared with that of conventional controller. Simulation results prove the efficacy of the proposed neural network based control for multi output SMPS. Improved power quality in terms of THD, almost unity power factor and voltage regulation are achieved for varying source and load condition.

Effect of heating power on the scrap tires pyrolysis derived oil

Experimental investigation is carried out in order to study the effect of power input on the pyrolysis process of waste tires (WT). Three different power input levels i.e., 750W, 1500W and 3000W have been used to heat the reactor to 500°C. The part of energy that was effectively consumed for thermal cracking of rubber and in evaporating the volatile products was deduced by subtracting reactor heating energy (blank tests) from total power input. Changes in physico-chemical characteristics of products were noticed while changing power inputs, which can be the consequence of changes in energy distribution between heating and cracking processes. In addition to the liquid product yield, its tar content is considered to be one of the most important characteristics according to the European standard EN590. From one side, the yield of liquid product for both 1500W and 3000W is higher than 45% while it is around 40% for 750W. On the other side, tar content in the liquid product is higher than 35% at 1500W and 3000W power inputs while it is around 11% at 750W. When high power is introduced to the reactor, it promotes the cracking of CC and CH bonds leading to higher liquid yield and H2 formation during the pyrolysis. Furthermore, it promotes dehydrogenation/cyclization/aromatization/reactions leading to tar and coke formation. Diels–Alders reaction mechanism explains as well the tar yield in the liquid product via dehydrogenation/aromatization/cyclization/reactions.