Double Path Research Articles

Metal foams as flow distributors in comparison with serpentine and parallel flow fields in proton exchange membrane electrolyzer cells

The arrangement of flow field in a proton exchange membrane electrolyzer cell (PEMEC) plays a significant role on distribution of reactants over the active area of electro-catalyst and transfer of products toward the outlet of PEMEC. In this paper, the performance of a PEMEC with metal foam as flow distributer is investigated and compared with two common flow fields. A numerical analysis is conducted based on a three-dimensional model of an electrolyzer with parallel pattern flow field (model A), double path serpentine flow field (model B), parallel flow field and metal foam as a flow distributor (model C), and a simple channel that is filled with metal foam (model D). The performance of four different models are compared to each other in terms of current density, temperature, hydrogen mass fraction and pressure drop distribution. The current density for model A, model B, model C, and model D at voltage of 1.55 V are 0.3, 0.41, 0.43 and 0.44 A/cm2, respectively. The results indicate that model D has the best performance in comparison with other models in terms of pressure drop and uniformity of hydrogen mass fraction and temperature. There is no significant difference between models B, C, and D in terms of current density, but the pressure drop in the model B, model C and model D are 736, 9.72, and 4.917 kPa, respectively. It is concluded that utilization of metal foams has advantages such as high electrical conductivity and low weight, and an appropriate foam permeability should be selected to optimize the pressure drop.

Lateral control of an autonomous vehicle using integrated backstepping and sliding mode controller

In this paper, a novel Lyapunov-based robust controller by using meta-heuristic optimization algorithm has been proposed for lateral control of an autonomous vehicle. In the first step, double lane change path has been designed using a fifth-degree polynomial (quantic) function and dynamic constraints. A lane changing path planning method has been used to design the double lane change manoeuvre. In the next step, position and orientation errors have been extracted based on the two-degree-of-freedom vehicle bicycle model. A combination of sliding mode and backstepping controllers has been used to control the steering in this paper. Overall stability of the combined controller has been analytically proved by defining a Lyapunov function and based on Lyapunov stability theorem. The proposed controller includes some constant parameters which have effects on controller performance; therefore, particle swarm optimization algorithm has been used for finding optimum values of these parameters. The comparing result of the proposed controller with backstepping controller illustrated the better performance of the proposed controller, especially in the low road frictions. Simulation of designed controllers has been conducted by linking CarSim software with Matlab/Simulink which provides a nonlinear full vehicle model. The simulation was performed for manoeuvres with different durations and road frictions. The proposed controller has outperformed the backstepping controller, especially in low frictions.

Global Estimates of Errors in Quantum Computation by the Feynman\u2013Vernon Formalism

The operation of a quantum computer is considered as a general quantum operation on a mixed state on many qubits followed by a measurement. The general quantum operation is further represented as a Feynman–Vernon double path integral over the histories of the qubits and of an environment, and afterward tracing out the environment. The qubit histories are taken to be paths on the two-sphere S^2 as in Klauder’s coherent-state path integral of spin, and the environment is assumed to consist of harmonic oscillators initially in thermal equilibrium, and linearly coupled to to qubit operators hat{S}_z. The environment can then be integrated out to give a Feynman–Vernon influence action coupling the forward and backward histories of the qubits. This representation allows to derive in a simple way estimates that the total error of operation of a quantum computer without error correction scales linearly with the number of qubits and the time of operation. It also allows to discuss Kitaev’s toric code interacting with an environment in the same manner.

English

English

Single and multiple Auger decay processes from the Ne+1s−12p−1np shake-up states studied with a multielectron coincidence method

The single, double, and triple Auger decay processes from the $1{s}^{\ensuremath{-}1}2{p}^{\ensuremath{-}1}np$ shake-up states of Ne have been studied with a multielectron coincidence method. It is revealed that the Rydberg electron promoted in the initial photoionization step generally acts as a spectator both in the single and double Auger decays. The single Auger decay predominantly produces three-hole one-particle final states while leaving the Rydberg electron virtually unchanged. In the cascade double Auger paths, the Rydberg electron is a spectator in the first step of the cascade process but is subsequently released in the second step, leading to the formation of three-hole final states. The direct paths of double Auger decays, which are much weaker than the cascade paths, produce preferably four-hole one-particle states due to the spectator behavior of the Rydberg electron. The distributions of the $\mathrm{N}{\mathrm{e}}^{4+}$ states populated by the triple Auger decays are also presented.

Investigation of the Double Current Path Phenomenon in Gate-Grounded Tunnel FET

Gate-grounded tunnel field-effect transistors (ggTFETs) are considered as basic electrostatic discharge (ESD) protection devices in TFET-integrated circuits. It has been reported that two current paths exist when the ggTFET is turned on under the ESD events. In this letter, the double current path phenomenon in ggTFETs is further investigated using TCAD simulation. It is found that the upper path is a hole current path, while the lower path mainly consists of electrons, and the grounded gate is a major factor that influences the double current path phenomenon. The heat and lattice temperature distributions in ggTFETs are also discussed.

Research on the signal of 4He pump magnetometer sensor using ECDL laser

One of the most important factors determines specifications of 4He optically pumped magnetometer is the quality of resonance signal given by sensor probe. This paper introduces a laser 4He optically pumped magnetometer using an ECDL laser. An external cavity length tuning system of ECDL laser based on the double light path atom saturated absorption spectrum method with a 4He cell is build up to ensure that an effective 1083.207 nm laser light source is provided for the magnetometer probe. It is designed a double path photoelectric detector to get the absorption peak signal by the difference technology. Because signal in accordance with Lorentz linear features, a detection method combined with first and second derivative of signal curve is proposed. Join a modulation signal whose form is dc component add sinusoidal component, the system make ECDL laser give a stable output wavelength around 1083.207 nm. With the laser light, a resonance signal with better quality than the 4He optically pumped magnetometer probe using the gas discharge lamp light source is given.

Novel dual channel polarization interference imaging system

The interference images with fixed spectral resolution can be obtained by using the existing static polarization-difference imaging system because the optical path of the system cannot be changed flexibly. However, for different detection targets, the spectral resolution of the system determined by the optical path difference must be appropriate. To satisfy a variety of application requirements, a novel dual channel polarization-difference interference imaging system (DPDⅡS), based on the lateral shear of the wide-field-of-view Savart polariscope (WSP) and the modulated Savart polariscope (MSP), is presented. The two-dimensional space images of a target and orthogonal interference images can be obtained by adjusting the MSP under different lateral displacements simultaneously. In addition, the remarkable characteristics of the system avoid spilling over rays and optimizing the system optical path effectively. In this paper, by using the Jones matrix, the system structure is demonstrated and the theoretical principle of DPDⅡS is analyzed in detail. The amplitudes of the four beams from the MSP and the interference intensity expressions of the coherent light are derived. Then the splitting characteristics of the Savart polariscope (SP) and WSP are presented. It is concluded that the WSP has better shear ability than SP and the WSP can optimize the optical path effectively compared with Wollaston prism in the DPDⅡS. The change ranges of the optical path difference and lateral displacement produced by the MSP for structure angles =/3, /4, /6 are analyzed in detail. The reconstructed orthogonal interferograms and the experimental interferograms under 632.8 nm monochromatic light for dMSP=1.00, 1.10, 1.20, 1.30 mm are obtained. A comparison between the experimental interference images and the simulated images proves that the interference fringes with different resolutions can be obtained simultaneously by adjusting the MSP. Meanwhile, the light intensities of the double optical paths are approximately equal and the same optical path difference is generated for the dual channel with the movement of MSP. The experimental results are consistent with the theoretical analyses. The spatial images of parallel and vertical components are detected under 632.8 nm polychromatic light. Then the total intensity image and the polarization-difference image are obtained through data processing. The conclusion that the polarization difference intensity image has a high resolution compared with the polarization intensity image is presented. The study has reference significance and practical value for the dual channel polarization interference imaging system.

Compact Biocompatible Fiber Optic Temperature Microprobe Using DNA-Based Biopolymer

A highly compact biocompatible microprobe type fiber optic temperature sensor was experimentally demonstrated utilizing an inherently high thermo-optic coefficient of DNA biopolymer. The sensor was based on an all-fiber multimode interferometer (MMI) along a coreless silica fiber (CSF) spliced to an end of a single mode fiber. Au film was deposited the CSF end facet to provide a double path for MMI and it also worked as a probe terminal. The circumferential area of CSF was coated with DNA-cetyltrimethylammonium chloride (CTMA) thin solid film, which served as a temperature sensing head. We experimentally investigated thermo-optical properties of DNA-CTMA thin solid films to find its large negative thermo-optical coefficient −4.15 × 10−4/°C in the temperature range from 20 to 70 °C. DNA-CTMA coated fiber optic probe was immersed in a water bath to simulate the bio compatible environment whose temperature was varied in the range from 30 to 70 °C. The proposed sensor showed a high-temperature sensitivity of −0.22 nm/°C in the spectral shifts, and 0.085 dB/°C in the reflected optical power changes. The proposed probe can be readily applied in various types of in vivo point of care temperature monitoring.

Optimal Trajectory Control for Capturing a Mobile Sound Source by a Mobile Robot

This paper presents a novel trajectory planning optimization process for a mobile robot to capture a mobile sound source (MSS) efficiently. The sound source can be an arbitrary object for the mobile robot to follow, such as a human being. The mobile robot is equipped with a microphone array so that it can obtain the location and direction of the MSS. During the capturing process, the location and direction of the MSS need to be known in advance so that an optimal path for capturing the sound source can be generated based upon a single or a double curvature path. Also a path predictive algorithm is used to estimate the moving path of the sound source. The conventional Kalman filter is used to realize an efficient prediction process for the mobile robot to capture the sound source quickly and accurately. The validity of the proposed algorithm has been demonstrated through its application in real experiments.

The clinical efficacy of double stent method with silicone tubes for the treatment of lacrimal canaliculus laceration

Objective To investigate the efficacy of double stent intubation with silicone tubes for the treatment of lacrimal canaliculus laceration. Methods The lacrimal canaliculus rupture ends was found under the surgical microscope by the methods of direct search, gas injection, water injection and the probe guiding. All cases received the silicone stent into the nasolacrimal duct through the double path. The anastomosis lacrimal canaliculus ends were sew up reduced tension. Results Twenty-six eyes of 26 cases with lacrimal canaliculus laceration underwent the surgery. The symptom of epiphora disappeared and lacrimal irrigation unobstructed in 23 cases. Two cases occurred narrow lacrimal when it was irrigated in 1 week after extubation, with mild epiphora. The symptom of epiphora, and obstructed lacrimal irrigation happened in 1 case. Twenty-three cases (88.46%) were cured completely, 2 cases (7.69%) were improved, 1 case was invalid (3.85%). Conclusion The surgery of double canalicular stent method with silicone tube for the lacrimal canaliculus laceration is simple and little damage. Key words: Silicone stent; Double catheter method; Lacrimal canaliculus laceration

An X-FEM approach for simulation of 3-D multiple fatigue cracks and application to double surface crack problems

The extended finite element method (X-FEM) is a promising and efficient tool to calculate stress intensities in fatigue crack growth analysis. An X-FEM approach is presented to simulate the fatigue growth of 3-D multiple cracks. Level set functions are used to characterize the cracks. A novel explicit/implicit hybrid description of cracks is introduced to follow up the crack growth and update level set functions, in which the reconstruction of crack surface is suggested to keep the crack smooth in crack growth simulation. The crack linking-up is also modeled with the hybrid description scheme. A stable partition algorithm is introduced to perform robust integration in the elements with discontinuities. The interaction integral method is adopted to evaluate the mix-mode stress intensity factors and the crack growth are characterized by mix-mode Paris law. As a practical application, the fatigue crack growth simulations are conducted on 30CrMnSiA steel alloy specimens with coplanar and non-coplanar double surface cracks. The simulated double crack growth paths and their coalescence behavior agree well with the experimental results. The proposed hybrid crack description method is efficient and with low computational cost.

The Optimization Design of VFTO Measuring Method

Whether VFTO can be fast accurate measured becomes an important index of GIS substation equipment safety. The research in this article used the optical voltage measuring method, through the simulation results of single photon road to analyze the advantages and disadvantages, furthermore the double optical path method was put forward, and by the simulation the feasibility of optimization was proved.

Q-switched slab RF discharge CO laser

A compact repetitively pulsed cryogenically cooled slab RF discharge CO laser with double path V-type laser resonator equipped with external Q-switching system based on rotating mirror was developed and studied. The laser produced mid-IR (λ ~ 5–7 µm) radiation pulses of ~1 ÷ 2 µs duration (FWHM), peak power up to ~3 kW, and pulse repetition rate up to 130 Hz. Averaged output laser power reached 0.5 W, the laser spectrum consisted of ~80 laser lines with individual peak power up to 80 W.

An experimental and numerical investigation of the use of liquid flow in serpentine microchannels for microelectronics cooling

This paper presents a combined experimental and numerical investigation of single-phase water flow and heat transfer in serpentine rectangular microchannels embedded in a heated copper block. The performance of four different microchannel heat sink (MCHS) configurations are investigated experimentally, the first having an array of straight rectangular microchannels (SRMs), while the other have single (SPSMs), double (DPSMs) and triple path multi-serpentine rectangular microchannels (TPSMs). Three-dimensional conjugate heat transfer models are developed for both laminar and turbulent single-phase water flows in each of these MCHSs and the governing flow and energy equations solved numerically using finite elements. The numerical predictions of pressure drop (ΔP) and average Nusselt number (Nuavg) are in good agreement with experimental data, and indicated that the single path serpentine microchannel (SPSM) leads to a 35% enhancement of the Nuavg at a volumetric flow rate of 0.5l/min and a 19% reduction in total thermal resistance (Rth) compared to the conventional SRM heat sink. However, this enhancement is at the expense of a large (up to ten-fold) increase in ΔP compared to the SRM heat sink, so that a suitable compromise must be struck between heat transfer and pressure drop in practical MCHS designs.

Diversity in Economics: A Gender Analysis of Italian Academic Production

Economists’ infamous failure at predicting the recent financial crisis has brought new impetus to studies on diversity in the economics profession. Such studies have underlined how diversity plays a prominent role in enriching economic analyses. The main purpose of this article is to provide new insights into the degree of gender diversity: rather than looking at women’s presence in academia only, we extend our focus to the research production by academic economists in the last few decades. The tendency to identify research quality with standardized bibliometric indicators – i.e. impact factor or h index – had consequences in term of heterogeneity of researchers within institutions (at all levels), and, most of all, in terms of pluralism of research interests. Our new data uncovers a double convergence path: i) a progressive reduction in the variety of research interests of women and men economists; ii) a tendency to “homologate” with international standards of perceived research ‘excellence’. As a consequence of such an impoverishment of pluralism in research, the academic production of both men and women has been drifting away from non-mainstream fields, and, in particular, from heterodox approaches and from the history of economic thought. Since women’s academic careers remain markedly characterized by a strong vertical segregation, we find that for women this effect is even stronger since they are more subject to homologating their research activities with respect to that of their male colleagues.

Method for Detection of the Lean Meat Ratio in Pork Carcass Based on Fiber Optic Sensor

One of the main evaluations in pork carcass is the lean meat ratio. A method based on Fiber optic sensor and NIR (Near Infrared) to acquire the ratio was put forward. This method acquired the reflected light intensity of the meat inside the pork carcass, by using double optical paths to reduce the errors caused by the instability of light. The fiber was lead into a probe which can be stabbed into the pork carcass, and then the reflected light was detected by a circuit named LIA (lock in amplifiers) to recognize the weak reflected light intensity effectively. The results suggested that the reflected light of the fat part of the pork was much higher than that of lean part, and through medium filter, the conditions of fluctuation was improved. The system was proved to be quick and accuracy for the detection of lean meat ration in pork carcass.

Clinical study of the treatment principle of Yangyin-Huayu for the patients with recurrent hemoptysis of bronchiectasis

Objective To observe the clinical curative effect and the serum CPR changes by the treatment principle of Yangyin-Huayu for the patients with recurrent hemoptysis of Bronchiectasis. Methods A total of 64 patients were enrolled and divided into 2 groups according to the random number table method, 32 patients in each group. The control group was treated with the injection of blood clotting enzyme, pituitrin, levofloxacin lactate. And the treatment group was treated with the Yangyin-Huayu on the basis of the control group. Two groups were treated for 10 days. The CPR was detected by the double optical path immune turbidity analyzer. And the clinical effects, symptoms and signs scores were compared between before and after treatment and between two groups. Results Compared with the total effective rate of control group 84.38%(27/32), the treatment group was 96.88% (31/32) and significantly high (χ2=6.372, P<0.01). After treatment, the levels of serum CPR (2.45 ± 1.42 mg/L vs. 6.19 ± 2.34 mg/L, t=4.671) in the treatment groupwas significantly lower than that in the control group (P<0.01). The scores of cough (0.62 ± 0.91 vs. 1.34 ± 0.58, t=5.364), sputum (0.14 ± 0.28 vs. 0.68 ± 0.72, t=4.035), haemoptysis (0.10 ± 0.65 vs. 0.62 ± 0.26, t=5.012), fever (0.04 ± 0.31 vs. 0.76 ± 0.07, t=3.026), breathing difficulties (0.12 ± 0.41 vs. 0.69 ± 0.05, t=4.010) in the treatment group were lower than those in the control group (P<0.01). Conclusions The treatment principle of Yangyin-Huayu combined with conventional western medicine therapy can improve the patients with recurrent hemoptysisin the fields of symptoms, signs, the serum level of CPR, and total effect rates. Key words: Bronchiectasis; Hemoptysis; Hemostatics (TCD); Removing blood stasis for hemostasis; Nourishing Yin and hemostasis; Integrated Chinese traditional and western medicine therapy

Design, manufacturing and measurement of aspheric test-plate using only traditional techniques

A plano-aspheric test-plate was designed, manufactured and measured. The design was achieved using an optical design software (ZEMAX). A traditional manufacturing method was applied to fabricate the aspheric test-plate from a spherical one using a spherometer with many rings and local removal polishing. An interferometric double path auto-collimation measuring method was used to measure surface’s parameters. This aspheric test plate was used in the workshop to fabricate and evaluate other aspheric lenses using Newton’s rings. The resolution of the aspheric test-plate and the manufactured lenses was measured in order to evaluate their performance by comparison with spherical lenses. All processes are made using traditional methods. The final results may be useful to encourage traditional optical work-shops to produce such important surfaces.

Modeling and Verification of 7 DOF Armored Vehicle Model Considering Lateral Dynamics

This paper presents the modeling of a 7 DOF Armored Vehicle. It includes load distribution, tire model, wheel model, handling model, yaw effect and side slip angle. All the mathematical equation will be derived in this paper and the modeling is developed using a MATLAB SIMULINK software. Then, the model is verified with the graph obtained by CarSim. A test procedure of double lane change driver path follower is used for the verification. Lastly, the results obtained by the simulation and CarSim validation will be discussed in term of its trend and similarity. Validation results showed that the developed model presents similar trend with CarSim results. The validated armored vehicle model can be used for further research such as developing a lane tracking system based on input given using a robotic driver system which act as actuator.