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Establishing correct correspondences between two images should consider both local and global spatial context. Given putative correspondences of feature points in two views, in this paper, we propose Order-Aware Network, which infers the probabilities of correspondences being inliers and regresses the relative pose encoded by the essential or fundamental matrix. Specifically, this proposed network is built hierarchically and comprises three operations. First, to capture the local context of sparse correspondences, the network clusters unordered input correspondences by learning a soft assignment matrix. These clusters are in canonical order and invariant to input permutations. Next, the clusters are spatially correlated to encode the global context of correspondences. After that, the context-encoded clusters are interpolated back to the original size and position to build a hierarchical architecture. We intensively experiment on both outdoor and indoor datasets. The accuracy of the two-view geometry and correspondences are significantly improved over the state-of-the-arts. Besides, based on the proposed method and advanced local feature, we won the first place in CVPR 2019 image matching workshop challenge and also achieve state-of-the-art results in the Visual Localization benchmark. Code is available at https://github.com/zjhthu/OANet.

Valve controlled electro-hydraulic technology is widely used in heavy-duty linear actuator, but its energy efficiency is low. The electro-mechanical actuator (EMA) has high energy efficiency, but its output force is small. In order to achieve high efficiency, high power to weight ratio, and high performance linear drive, a hydraulic-electric hybrid linear drive principle integrating hydraulic cylinder and EMA is proposed, and a prototype of electromechanical hydraulic hybrid actuator (EMHA) is designed and developed. In the hybrid drive system, EMA is responsible for actuator motion control and hydraulic cylinder is used for force control. In the study, an extended state observer (ESO) was first designed to estimate the external load torque of the EMA permanent magnet synchronous motor (PMSM) in real time. Combining the detected pressures, the load force of the EMHA can be estimated. Then, according to the estimated load force, the hydraulic system is controlled to make the hydraulic cylinder balance most of the actuator load force, maintaining the PMSM within the required load range. A sliding mode controller is further designed to compensate the external load torque acting on the PMSM to ensure that the system has good motion control characteristics. The results show that under the same driving force and velocity, the power density of the EMHA is 154% higher than that of the EMA. The proposed system can achieve equivalent control performance as the valve controlled system, while reducing energy consumption by 58%.

Back-stepping design method is widely used in high-performance tracking control tasks As is known to all, the controller based on back-stepping design will become complex as the model order increases, which is the so called “explosion of terms” problem. In this paper, a tracking differentiator (TD) based back-stepping controller is proposed to handle the “explosion of terms” problem. Instead of calculating the derivatives of intermediate control variables through tedious analytical expressions, for the proposed method, the tracking differentiator is embedded into each recursive procedure to generate the substitute derivative signal for every intermediate control variable. As a result, the complexity of implementation procedure of back-stepping controller is significantly reduced. The discrepancies between the derivative substitutes and the real derivatives are considered. And the effects on control performances caused by the discrepancies are analyzed. In addition to giving the theoretical results and the stability proofs with Lyapunov methods, the developed controller design method is evaluated through a series of experiments with a hydraulic robot arm position serve system. The control performance of the proposed controller is verified by the experiments results.

The detection of volatile organic compounds by gas sensors is of great interest for environmental quality monitoring and the early-stage and noninvasive diagnosis of diseases. Experiments found hexane, toluene, aniline, butanone, acetone, and propanol gases in the exhaled breath of patients suffering from COVID-19, lung cancer, and diabetes. However, no studies are available to systematically elucidate the selectivity of these gases on nanosheets of zinc oxide for chemiresistive and direct thermoelectric gas sensors. Therefore, this work performed the elucidation by studying the electronic, electrical, and thermal properties of the bilayered ZnO nanosheets with polar (0001) and non-polar (112̄0) surfaces under the adsorption of the gases. The interaction between the gases and the nanosheets belongs to two groups: electrostatic attraction and charge exchange. The second one occurs due to the peak resonance of the same type of orbitals between the substrates and the gases along the surface normal and the first one for the other cases. The characteristics of the Seebeck coefficient exhibited distinct selectivity of butanone and acetone.

The direct methanol fuel cell (DMFC) is among the most promising alternative energy sources for the near future owing to its advantages of simple construction, compact design, high energy density, and relatively high energy-conversion efficiency. Typically, the electrodes in DMFC is comprised of a Pt-based catalysts supported on great potential of carbon materials such as multi-walled carbon nanotubes (MWCNTs), carbon black (CB), graphene, etc. It is desired to develop an electrode with high surface area, good electrical conductivity and suitable porosity to allow good reactant flux and high stability in the fuel cell environment. This chapter will provide recent advances in Pt-based binary and ternary electrocatalysts on carbon supports for high-performance anodes in DMFC. Through studying the effects of composition-, support-, and shape dependent electrocatalysts, further fundamental understanding and mechanism in the development of anode catalysts for DMFC will be provided in details.

With the widespread application of the computer and microelectronic technology in the industry, digitization becomes the inevitable developing trend of the hydraulic technology. Digitization of the hydraulic components is critical in the digital hydraulic technology. High-speed on-off valves (HSVs) which convert a train of input pulses into the fast and accurate switching between the on and off states belong to widely used basic digital hydraulic elements. In some ways, the characteristics of the HSVs determine the performance of the digital hydraulic systems. This paper discusses the development of HSVs and their applications. First, the HSVs with innovative structures which is classified into direct drive valves and pilot operated valves are discussed, with the emphasis on their performance. Then, an overview of HSVs with intelligent materials is presented with considering of the switching frequency and flow capacity. Finally, the applications of the HSVs are reviewed, including digital hydraulic components with the integration of the HSVs and digital hydraulic systems controlled by the HSVs.

This article presents a comprehensive, multidisciplinary overview of the development of powertrain technologies for energy-efficient heavy-duty earthmoving machines. The heavy-duty earthmoving equipment industry has been among the biggest contributors to emissions globally. However, due to high power demand and multidisciplinary powertrain structures, improving the energy efficiency of heavy-duty mobile machines has been a pressing and challenging task in the industry. To cope with this challenge, hydraulics and power electronics (PE) have been the key driving forces. As such, the relative developments in both fields are covered in this article. For hydraulics, developments of efficient hydraulic circuits will be overviewed in detail along with the introduction of hydraulic energy recovery technologies. In addition, developments of PE architectures in hybrid and electrified machines will be introduced. Furthermore, potential medium-voltage dc mining site power distribution and the valves of wide bandgap devices will also be discussed with the hope to open up new research opportunities in PE. Moreover, emerging hybrid electrohydraulic drive technology is introduced. Based on the overview in this article, it is anticipated that electrohydraulic hybridization will be the future trend in the earthmoving machine industry. Deeper collaboration between the two areas is desirable.

Fused deposition modeling (FDM) processed Poly-ether-ether-ketone (PEEK) materials are widely used in aerospace, automobile, biomedical, and electronics industries and other industries due to their excellent mechanical properties, thermal properties, chemical resistance, wear resistance, and biocompatibility, etc. However, the manufacture of PEEK materials and parts utilizing the FDM process faces the challenge of fine-tuning a list of process parameters and heat treatment conditions to reach the best-suiting mechanical properties and microstructures. It is non-trivial to make the selection only according to theoretical analysis while counting on a vast number of experiments is the general situation. Therefore, in this paper, the extrusion rate, filling angle, and printing orientation are investigated to adjust the mechanical properties of 3D-printed PEEK parts; then, a variety of heat treatment conditions were applied to tune the crystallinity and strength. The results show that the best mechanical performance is achieved at 1.0 times the extrusion rate, varied angle cross-fillings with ±10° intervals, and vertical printing. Horizontal printing performs better with reduced warpage. Additionally, both crystallinity and mechanical properties are significantly improved after heat treatment, and the best state is achieved after holding at 300 °C for 2 h. The resulting tensile strength is close to 80% of the strength of injection-molded PEEK parts.

Generally, during the accelerating process of construction machinery large inertia hydraulic swing system, a lot of kinetic energy is accumulated, and it will be eventually dissipated through the relief valve orifice during the decelerating process, which results in serious energy waste and large overflow loss. In order to solve this problem, a new dual source hydraulic motor with non-uniform flow distribution is proposed, which can drive high-frequency swing mechanism efficiently. The new dual source hydraulic motor has two groups of oil inlet and outlet, corresponding to two groups of different displacement. The two groups of inlet and outlet are respectively connected with the energy recovery unit and the main driving unit. During the starting process, the energy recovery unit assists the main driving unit to drive the swing mechanism together, so that the main drive unit output torque and overflow loss are reduced; during the braking process, the energy recovery unit recovers the braking energy. Finally, the integrated control of braking energy direct recovery and utilization is realized. In the research, the 38 t hydraulic excavator is taken as the research object. Firstly, the multi-body dynamics electro-hydraulic simulation model of the dual source integrated driving hydraulic excavator swing system is established, and the accuracy of the model is verified by experiments. Then the effects of the accumulator working pressure and the dual source hydraulic motor displacement ratio on the working performance of the system were simulated. The simulation results show that with the displacement ratio increasing, the accelerating time, the maximum angular velocity and decelerating time increase. Compared with the original system, when the displacement ratio $\alpha $ is 0.6, the comprehensive performance of the system is the best, and the hydraulic pump output energy is reduced by 48.6% and 46.6% respectively in the process of full load and no-load operation.

In this paper, to improve the convergence speed of the block-diagonal and anti-block-diagonal splitting (BAS) iteration method, we design a modified BAS (MBAS) method to obtain the numerical solution of the absolute value equation. Theoretical analysis shows that under certain conditions the MBAS method is convergent. Numerical experiments show that the MBAS method is feasible.

Environmental and maternal exercise experienced even during the very earliest stages of life has the potential to cause developmental changes. The growing evidence demonstrated that diverse environmental stressors affect offspring in various aspects in early stage of life and can be transmitted directly or indirectly by both parental lines. The development of normobaric hypoxic environment facilities began in recent years after athletes born and trained at high altitude continued to update their records in sports competition, especially marathons and other endurance sports. Although a large number of studies have proved the effect of hypoxic training in the field of sports science and competition, the effectiveness of this training model on exercise performance/capacity and physiological variables is still controversial. Therefore, this study makes a brief review of the papers related to this scope and attempted to understand the potential mechanism of maternal exercise in hypoxic environment on exercise performance and reduction of metabolic risk factors.

The provision of social work services at district health centers are not well reported in previous studies. This study aimed to report the results of the provision of social work services at Dakto District Health Center, Kon Tum province, Vietnam, and to find out factors affecting this provision. This was a cross-sectional study that used secondary data, 13 in-depth interviews, and 2 focus group discussions to collect data. Among the social work services prescribed by the Ministry of Health, Dakto District Health Center provided the following four services: information instruction and consultation services, and psychological support for patients; communication and health promotion services; services in support of health workers; and resources mobilization and coordination services. Our study found factors that hinder the provision of social work services at the center and suggested policies to the related parties.

Mining shovel has been the most critical equipment for high-efficiency production in open-pit mining, it adopts electric motor to drive hoisting and slewing system separately. However, in the process of falling the hoisting device and decelerating the slewing platform, the driving motors are in the power generation state, and the electric energy is dissipated in the form of heat energy through the braking resistor, which causes a large amount of energy waste. To achieve energy saving, this article proposes a novel hydraulic-electric hybrid driving system. In the proposed system, the auxiliary hydraulic system is used to store the energy generated by the motor in the form of hydraulic accumulator pressure. When the hoisting system lifts or slewing platform accelerates, the energy is reused to assist the motor in the form of supporting torque. The recovery and reuse of the dynamic potential energy of the shovel can reduce the energy loss and installed power of the driving motor. In addition, the additional supporting torque also increases the safety of the pure electric drive system. In this paper, firstly, the hydraulic-electric hybrid driving principle is introduced. Then, a small-scale testbed is set up to verify the feasibility of the system. Finally, a co-simulation model of the proposed system is established to clarify the system operation and energy consumption characteristics, and to analyze the impact of different parameters of key energy storage components on system performance. Through the test and simulation of the proposed system, compared with the traditional purely electric driving system, the peak power and energy consumption of the hoisting motor are reduced by 36.7% and 29.7%, and those of the slewing motor are decreased by 86.9% and 59.4%, respectively.

This paper presents an interpolation-based method (IBM) for approximating some trigonometric functions or their integrals as well. It provides two-sided bounds for each function, which also achieves much better approximation effects than those of prevailing methods. In principle, the IBM can be applied for bounding more bounded smooth functions and their integrals as well, and its applications include approximating the integral of sin(x)/x function and improving the famous square root inequalities.

Elevator has been the most critical equipment for vertical transportation and one of the largest energy consumption sources in buildings. The main cause of energy waste in elevator is the dissipation of the energy regenerated by the motor. To achieve energy saving, this article proposes an electro-hydraulic hybrid driving elevator system. With an auxiliary hydraulic system, the energy generated by the motor can be stored in the form of hydraulic accumulator pressure, which can be reused to assist motor start in the form of supporting torque. In addition, due to the additional torque provided by the hydraulic system, elevator safety can be enhanced. Simulation results have been obtained, demonstrating that large amount of energy can be saved with the proposed system. Field test results with elevator in a real building environment are also presented to verify the efficacy of the proposed idea.

Unsteady motion of the atmosphere incurs nonlinear and spatiotemporally coupled uncertainties in the wind power prediction (WPP) of multiple wind farms. This brings both opportunities and challenges to wind power probabilistic forecasting (WPPF) of a wind farm cluster or region, particularly when wind power is highly penetrated within the power system. This paper proposes an Improved Deep Mixture Density Network (IDMDN) for short-term WPPF of multiple wind farms and the entire region. In this respect, a deep multi-to-multi (m2m) mapping Neural Network model, which adopts the beta kernel as the mixture component to avoid the density leakage problem, is established to produce probabilistic forecasts in an end-to-end manner. A novel modified activation function and several general training procedures are then introduced to overcome the unstable behavior and NaN (Not a Number) loss issues of the beta kernel function. Verification of IDMDN is based on an open-source dataset collected from seven wind farms, and comparison results show that the proposed model improves the WPPF performance at both wind farm and regional levels. Furthermore, a laconic and accurate probabilistic expression of predicted power at each time step is produced by the proposed model.

The increasing scale of Structure-from-Motion is fundamentally limited by the conventional optimization framework for the all-in-one global bundle adjustment. In this paper, we propose a distributed approach to coping with this global bundle adjustment for very large scale Structure-from-Motion computation. First, we derive the distributed formulation from the classical optimization algorithm ADMM, Alternating Direction Method of Multipliers, based on the global camera consensus. Then, we analyze the conditions under which the convergence of this distributed optimization would be guaranteed. In particular, we adopt over-relaxation and self-adaption schemes to improve the convergence rate. After that, we propose to split the large scale camera-point visibility graph in order to reduce the communication overheads of the distributed computing. The experiments on both public large scale SfM data-sets and our very large scale aerial photo sets demonstrate that the proposed distributed method clearly outperforms the state-of-the-art method in efficiency and accuracy.

There are the problems in the traditional pressure-compensation flow-control valve, such as low flow control accuracy, small flow control difficulty, and limited flow range. For this, a method of continuous control pressure drop Δprated (i.e. the pressure drop across the main throttling orifice) to control flow-control valve flow is proposed. The precise control of small flow is realized by reducing the pressure drop Δprated and the flow range is amplified by increasing pressure drop Δprated. At the same time, it can also compensate the flow force to improve the flow control accuracy by regulating the pressure drop Δprated. In the research, the flow-control valve with controllable pressure compensation capability (FVCP) was designed firstly and theoretically analyzed. Then the sub-model model of PPRV and the joint simulation model of the FVCP were established and verified through experiments. Finally, the continuous control characteristics of pressure drop Δprated, the flow characteristics, and flow force compensation were studied. The research results demonstrate that, compared with the traditional flow-control valve, the designed FVCP can adjust the compensation pressure difference in the range of 0∼3.4 MPa in real-time. And the flow rate can be altered within the range of 44%∼136% of the rated flow. By adjusting the compensation pressure difference to compensate the flow force, the flow control accuracy of the multi-way valve is improved, and the flow force compensation effect is obvious.

In the hydraulic lifting systems of wheel loaders, the valve controlled systems are used to drive the hydraulic cylinder to complete frequent lifting and falling operations. The gravitational potential energy of the lifting system, accumulated in the lifting process, is converted into heat energy through the throttling port of the valve during the falling processes, which results in significant throttling loss and severe system overheating. To solve the problems, a potential energy regeneration and utilization system is proposed, where the closed loop pump controlled circuit based on the gravity self-balancing hydraulic cylinder is adopted to eliminate throttling loss, and the gravity self-balancing chamber of the cylinder is directly connected with accumulator to recycle gravity potential energy. In the research, the structure and working principle of the proposed hydraulic system is analyzed first, then the co-simulation model and the test prototype are established to investigate the working and energy characteristics of the proposed system. Test results indicate that, compared with the traditional valve controlled hydraulic system, 58.9% energy consumption reduction can be expected for the hydraulic pump by adopting the proposed system under the same working condition.

To meet the requirements of the high-precision operation of intelligent excavator, a dual power source coordinated control strategy of hydraulic-electric hybrid swing system is proposed. In the process of rotation, the servo motor is used as the main drive to control the speed and position of the swing platform. The hydraulic motor and accumulator auxiliary servo motor drive the swing platform to make it run to the desired position accurately and smoothly at the desired speed. Firstly, this paper established the mathematical model of the proposed system and designed the global synovial control algorithm. Then the stability of the proposed system was proved by the Lyapunov method. Then, the multi-body dynamics co-simulation platforms of the original excavator negative flow swing system and the proposed system were established. The operational characteristics of two kinds of swing systems were studied. The results show that compared with the original negative flow swing system, the proposed system can effectively suppress the anti-swing phenomenon, and the operation is more accurate and stable. Compared with PID, the global sliding mode control has higher accuracy and better robustness, and the control accuracy is as high as 99.71%.

Hydraulic systems are widely used in construction machinery and equipment. However, the energy efficiency of hydraulic system is low. In many cases, hydraulic systems output energy to lift the working device. During the lowering process, the potential energy is commonly wasted through the throttling loss of the control valve. Recovering the potential energy is an efficient way to improve the hydraulic system efficiency. In this article, theoretical analysis, simulation calculation, and experimental verification were used to study the energy recovery efficiency of a differential cylinder system controlled by variable displacement asymmetric axial piston pump. Meanwhile, the influence of the load, motor speed, variable displacement asymmetric axial piston pump swashplate angle, accumulator pressure and capacity, and other key parameters on the potential energy recovery efficiency and system performance was analyzed. The results show that the system energy consumption can be reduced effectively by using the potential energy recovery system. When the load, motor speed, pre-charge pressure and capacity of the accumulator, and swashplate angle are 440 kg, 1000 r/min, 2.5 MPa, 1.6 L, and ±5°, respectively, the system’s energy-saving effect can be up to 39.25%. Considering that only the vertical motion of the differential cylinder controlled by variable displacement asymmetric axial piston pump was analyzed, in future work, the corresponding parameter optimization and control strategy will be carried out to obtain good energy recovery effect, and the influence of accumulator pre-charge pressure on the energy-saving effect will be conducted.

In the current study, a numerical scheme based on the Haar wavelet is proposed to solve a coupled system of fractional-order integral–differential equations. The proposed method is to derive the operational matrix of fractional-order integration, and that is used to transform the main problem to a system of algebraic equations. Additionally, the convergence analysis theorem of this system is rigorously established and the numerical results show that the proposed method is practicable and effective for solving such kinds of problem.

In this paper, a smooth point-to-point trajectory planning method for industrial robots is proposed. The trajectory is planned in the joint space. The joint motion is divided into three parts, namely accelerated part, constant velocity part and decelerated part. In the accelerated part and decelerated part, the acceleration is planned with fourth-order polynomial formed with the property of the root multiplicity. Then near time-optimal trajectory can be obtained by maximizing the constant velocity part under kinematical constraints. The results show that the fourth-order polynomial formed with the property of the root multiplicity is determined by only one coefficient. Compared to the classical description, the arduous stage of solving the numerous polynomial coefficients can be eliminated. With the proposed trajectory planning method, the displacement, velocity, acceleration and jerk of each joint and end-effector are all continuous. At the initial moment and end moment, the velocity, acceleration and jerk of each joint and end-effector are zero. The velocity, acceleration and jerk of each joint meet the kinematical constraints. The end-effector moves smoothly and the proposed trajectory planning method is very effective.

Hydraulic excavators are essential excavation machines, with more than 3.8 million sets in use in the mining, and engineering and architectural engineering construction fields. However, during the working process, a large amount of gravitational potential energy is wasted, causing low energy efficiency and poor emissions. Taking a large-scale excavator as an example, during a certain 90° excavation process, the gravitational potential energy wastage of the working device is approximately 975.1 kJ, which amounts to at least 20% of the energy consumption of the entire machine, causing significant energy waste and serious pollution. And, during the boom lowering process, the changing rate of potential energy is about 406.4 kW. In order to improve the energy efficiency of hydraulic excavators, the recovery of this huge energy that changes rapidly with low cost and high efficiency is a big problem that must be solved. This paper proposes a gravitational potential energy recovery scheme with an energy conversion cylinder and a hydraulic accumulator. Using this scheme, the gravitational potential energy of the working device can be stored and reused directly, without increasing the cost and install power of the machine largely. In the study, first, the system parameters are designed, following which the multidisciplinary dynamic model of the hydraulic excavator is established. The influence of the accumulator parameters on the energy recovery ratio is studied based on the model. The results demonstrate that with the newly designed system more than 75.9% of the gravitational potential energy can be stored in the accumulator during the lowering process. Moreover, during a certain lifting process, the input energy to the pump can be reduced by 52%. On this basis, a 76 t hydraulic excavator test system is constructed using the above principle. The experimental results match strongly with the co-simulation results. The energy consumption can be reduced to approximately 238 kJ during a certain 90° excavation cycle, and the system can reduce the carbon dioxide emissions by 28088.4 kg per year. The energy-saving and emission-reduction effects are remarkable; furthermore, this principle can directly be applied to other lifting machines.

The present study is focused on a novel method for the acquisition of high-frequency sinusoidal vibration waveform with electro-hydraulic vibration exciter. A rotary valve controlled electro-hydraulic vibration exciter is proposed to make it easier to obtain high vibration frequency than the conventional servo valve controlled counterpart. Three common used offices are taken into consideration: rectangular orifice, triangular orifice, and semicircular orifice. Analytical solution to orifice design of shape and axial length is suggested for the accurate control of vibration waveform. Harmonic theory borrowed from electronic technology is used as an evaluation index for the shape of vibration waveform. The orifice shape design decision is made according to the total harmonic distortion of vibration waveform. The nonlinear differential equation which models vibration waveform is established. The orifice axial length is designed according to the supply pressure, vibration frequency, and amplitude. Both theoretical and experimental results show that rectangular orifice is desirable for high-frequency sinusoidal vibration waveforms. With the orifice design solution, the proposed vibration exciter can output the vibration waveform with total harmonic distortion of less than 1% as compared with sinusoidal waveform and maximum error of 5% as compared with experimental value at vibration frequency of higher than 100 Hz, and greatly extend the frequency bandwidth when sinusoidal vibration waveform is required.

Nowadays, the hydraulic pump driven by the diesel engine is widely used as the power unit for mobile machines, which consumes a large amount of fuel and cause high emissions. One solution is to use the electric driving mode. In this paper, the energy consumption characteristics of 4 electro-hydraulic power units, which are a fixed speed motor or a variable speed motor to drive a fixed displacement hydraulic pump or a variable displacement hydraulic pump, are compared and analyzed respectively. The results show that the power unit which a variable displacement hydraulic pump is driven by a variable speed asynchronous motor has the highest cost-performance ratio. However, due to the limitation of the battery peak current, the dynamic response of the power unit is slow. To solve this problem, a new power unit is proposed which add an accumulator to the hydraulic pump outlet to recover the power unit braking kinetic energy. The high-pressure oil stored in the accumulator can be absorbed into the hydraulic pump inlet to improve the power unit starting and braking performance and energy efficiency. The starting and braking characteristics of the power unit with and without the accumulator are compared experimentally. The results show that, if the power unit is driven by the motor alone, the power unit response is slow, and the load pressure has a significant influence on the response time. After adding the accumulator to the hydraulic pump, the power unit starting and braking time could be shortened significantly, and the starting power demand is also reduced. The proposed power unit is further used to drive a hydraulic excavator. Under the same working conditions and operating characteristics, energy consumption can be reduced by 28.5% compared with using the variable displacement hydraulic pump alone.

The operating temperature of hydraulic oils should be controlled within a reasonable range to keep hydraulic systems in good working condition. However, due to the huge energy losses of hydraulic systems, the oil temperature will increase rapidly. In addition, some hydraulic equipment often operate in cold weather conditions. The conventional cooling with radiators and preheating with electric heaters will consume extra energy for hydraulic systems. Therefore, an organic Rankine cycle with heat pump system is proposed to achieve regenerative cooling and energy-efficient preheating. The system can operate in two modes: an organic Rankine cycle mode to produce electricity instead of consuming energy while cooling the hot oil, and a heat pump mode to preheat the oil with less energy before the hydraulic system starts up in a cold environment. The system is applied to a 260-ton hydraulic excavator to investigate the technical feasibility. On average, the calorific power of the excavator is 177 kW at 245 kW of consumed power in a typical cycle. Considering the cost of heat source, the earning of equilibrium temperature is proposed to evaluate the benefit of the organic Rankine cycle. The optimal working fluid is selected by comparing the system performance. Afterward, the peak points of earning of equilibrium temperature at different ambient temperatures are observed. Corresponding to the maximum earning of equilibrium temperature, the output power of the organic Rankine cycle ranges from 7.63 kW to 2.89 kW. These results show significant energy savings by applying the proposed system in the hydraulic system.

The oscillator strengths and integral cross sections of the valence-shell excitations of HCl have significant applications in the studies of planetary atmospheres and interstellar gases. In the present work, the generalized oscillator strengths of the valence-shell excitations of HCl have been measured at an incident electron energy of 1500 eV and an energy resolution of 70 meV, and their momentum transfer dependence behaviors have been elucidated. It is observed that the generalized oscillator strength ratios of the b3Π1(ν' = 0) state to the C1Π(ν' = 0) state are a constant and independent of the squared momentum transfer, and this typical behavior in the momentum space is explained by the intraconfiguration mixing of the b3Π1 and C1Π states due to the spin-orbital interaction. The optical oscillator strengths of the valence-shell excitations have been obtained by extrapolating the generalized oscillator strengths to the limit of zero squared momentum transfer. The present optical oscillator strengths give an independent cross-check to the previous experimental and theoretical results, and it is found that most of the photoabsorption measurements are limited by the line saturation effect. The integral cross sections of the valence-shell excitations of HCl have been obtained systematically from the threshold to 5000 eV with the aid of the BE-scaling method.

The conventional design methods for tracked walking systems of large hydraulic excavators based on empirical formulas, does not take into account the dynamic load of the track. As such, a safety margin factor has to be adopted to ensure adequate working strength. However, the machine weight will be increased, and the hydraulic system will be overmatched. To address this design issue, an electromechanical–hydraulic design approach based on co-simulation is proposed in this study. The proposed design approach consists of four parts, namely, 1) a terramechanics model of the track that considers the pressure–sinkage relationship and soil shear stress of the individual tracked plate, 2) a tracked multibody dynamics (MBD) model that considers the intermittent transmission between the sprocket and the tracks, 3) the hydraulic systems model, and 4) the data communication interface. To demonstrate the proposed approach, it was used to design a large hydraulic excavator with a bucket capacity of 15 m3. Experimental results from the prototype showed that the proposed design principle can accurately reflect the impact load and periodic torque fluctuations on the track. The maximum error between the simulated and experimental results is 5.4% in forward walking and 12.7% in backward walking, thus demonstrating the effectiveness and accuracy of the proposed design approach.

Upon injury, the liver is capable of substantial regeneration from the original tissue until an appropriate functional size. The underlying mechanisms controlling the liver regeneration processes are not well elucidated. Previous studies have proposed that the transcription factor FoxO3 is involved in various liver diseases, but its exact role in the regulation of liver regeneration remains largely unclear. To directly test the detailed role of FoxO3 in liver regeneration, both a constitutive Albumin-Cre driver line and adeno-associated virus serotype 8 (AAV8)-Tbg-Cre (AAV-Cre)-injected adult FoxO3fl/fl mice were subjected to 70% partial hepatectomy (PH). Our data demonstrate that FoxO3 deletion accelerates liver regeneration primarily by limiting polyploidization and promoting the proliferation of hepatocytes during liver regeneration. RNA-seq analysis indicates that FoxO3 deficiency greatly alters the expression of gene sets associated with cell proliferation and apoptosis during liver regeneration. Chromatin immunoprecipitation-PCR (ChIP-PCR) and luciferase reporter assays reveal that FoxO3 promotes the expression of Nox4 but suppresses the expression of Nr4a1 in hepatocytes. AAV8 virus-mediated overexpression of Nox4 and knockdown of Nr4a1 significantly suppressed hepatocyte proliferation and liver regeneration in FoxO3-deficient mice. We demonstrate that FoxO3 negatively controls hepatocyte proliferation through Nox4 upregulation and Nr4a1 downregulation, thereby ensuring appropriate functional regeneration of the liver. Our findings provide novel mechanistic insight into the therapeutic mechanisms of FoxO3 in liver damage and repair.

Background: We aimed to identify the overlapping differentially expressed genes (DEGs) of keloids distinguished from normal scar and normal skin and relevant underlying mechanism using integrated bioinformatics methods.Methods: The expression profiles of 18 keloid samples, 7 normal skin and 5 normal scar, were obtained from the GSE7890, GSE44270, GSE92566, and GSE3189 datasets in the Gene Expression Omnibus database. DEGs were identified using the LIMMA package in R. Gene ontology (GO) functional enrichment analysis was performed using the R software. A DEG-associated protein–protein interaction (PPI) network was constructed using STRING and MCODE was used for module analysis of the PPI network. Moreover, the hub genes were verified by qRT-PCR. The predicted DEGs, their regulatory miRNA and TF regulation network was analyzed using miRnet. Results: A total of 978 common DEGs were identified in the keloid samples. Genes with more than 45 interaction degrees, including neuropeptide Y (NPY), opioid receptor mu 1 (OPRM1), cholinergic receptor muscarinic 2 (CHRM2), and proopiomelanocortin (POMC), were found in the PPI network. Hsa-miR-335 and Sp1 as upstream-regulators regulated CHRM2, NPY, and POMC. Functional enrichment analysis revealed that hub genes were commonly enriched in the “G protein-coupled receptor signaling pathway” GO_BP termConclusion: Taken together, CHRM2, NPY, POMC, and OPRM1 potentially have crucial roles in keloid disease. Furthermore, miR-335 and Sp1 are potential targets for preventing keloid formation.

Learning-based stereo matching has recently achieved promising results, yet still suffers difficulties in establishing reliable matches in weakly matchable regions that are textureless, non-Lambertian, or occluded. In this paper, we address this challenge by proposing a stereo matching network that considers pixel-wise matchability. Specifically, the network jointly regresses disparity and matchability maps from 3D probability volume through expectation and entropy operations. Next, a learned attenuation is applied as the robust loss function to alleviate the influence of weakly matchable pixels in the training. Finally, a matchability-aware disparity refinement is introduced to improve the depth inference in weakly matchable regions. The proposed deep stereo matchability (DSM) framework can improve the matching result or accelerate the computation while still guaranteeing the quality. Moreover, the DSM framework is portable to many recent stereo networks. Extensive experiments are conducted on Scene Flow and KITTI stereo datasets to demonstrate the effectiveness of the proposed framework over the state-of-the-art learning-based stereo methods., Accepted to ICPR 2020

Recent works on implicit neural representations have shown promising results for multi-view surface reconstruction. However, most approaches are limited to relatively simple geometries and usually require clean object masks for reconstructing complex and concave objects. In this work, we introduce a novel neural surface reconstruction framework that leverages the knowledge of stereo matching and feature consistency to optimize the implicit surface representation. More specifically, we apply a signed distance field (SDF) and a surface light field to represent the scene geometry and appearance respectively. The SDF is directly supervised by geometry from stereo matching, and is refined by optimizing the multi-view feature consistency and the fidelity of rendered images. Our method is able to improve the robustness of geometry estimation and support reconstruction of complex scene topologies. Extensive experiments have been conducted on DTU, EPFL and Tanks and Temples datasets. Compared to previous state-of-the-art methods, our method achieves better mesh reconstruction in wide open scenes without masks as input., Comment: ICCV 2021 (Oral)

Productivity is essential in the injection molding process, especially for plastic parts featuring thick walls. However, for this process, product elastic and plastic deformations after in-mold cooling impose severe constraints on productivity enhancement. Due to the complexity of the molding process, producing high-quality plastic parts in less cycle time is still difficult even with the help of advanced molding simulation packages. The authors propose a new ejection criteria model based on a recently published concept of partial solidification for early ejection in plastic part molding and investigate the general time determination model targeting to reduce the cycle time tremendously. A real industrial case study has been provided to show the procedure and its verification. Compared to the traditional ejection criterion which the plastic parts need to be fully solidified by in-mold cooling, with the new criteria, the cycle time could be significantly reduced if the plastic parts are ejected earlier with qualified and controlled partial solidification.

In this paper, we present a joint multi-task learning framework for semantic segmentation and boundary detection. The critical component in the framework is the iterative pyramid context module (PCM), which couples two tasks and stores the shared latent semantics to interact between the two tasks. For semantic boundary detection, we propose the novel spatial gradient fusion to suppress non-semantic edges. As semantic boundary detection is the dual task of semantic segmentation, we introduce a loss function with boundary consistency constraint to improve the boundary pixel accuracy for semantic segmentation. Our extensive experiments demonstrate superior performance over state-of-the-art works, not only in semantic segmentation but also in semantic boundary detection. In particular, a mean IoU score of 81.8% on Cityscapes test set is achieved without using coarse data or any external data for semantic segmentation. For semantic boundary detection, we improve over previous state-of-the-art works by 9.9% in terms of AP and 6.8% in terms of MF(ODS).

Recent learning-based approaches, in which models are trained by single-view images have shown promising results for monocular 3D face reconstruction, but they suffer from the ill-posed face pose and depth ambiguity issue. In contrast to previous works that only enforce 2D feature constraints, we propose a self-supervised training architecture by leveraging the multi-view geometry consistency, which provides reliable constraints on face pose and depth estimation. We first propose an occlusion-aware view synthesis method to apply multi-view geometry consistency to self-supervised learning. Then we design three novel loss functions for multi-view consistency, including the pixel consistency loss, the depth consistency loss, and the facial landmark-based epipolar loss. Our method is accurate and robust, especially under large variations of expressions, poses, and illumination conditions. Comprehensive experiments on the face alignment and 3D face reconstruction benchmarks have demonstrated superiority over state-of-the-art methods. Our code and model are released in https://github.com/jiaxiangshang/MGCNet.

Current bundle adjustment solvers such as the Levenberg-Marquardt (LM) algorithm are limited by the bottleneck in solving the Reduced Camera System (RCS) whose dimension is proportional to the camera number. When the problem is scaled up, this step is neither efficient in computation nor manageable for a single compute node. In this work, we propose a stochastic bundle adjustment algorithm which seeks to decompose the RCS approximately inside the LM iterations to improve the efficiency and scalability. It first reformulates the quadratic programming problem of an LM iteration based on the clustering of the visibility graph by introducing the equality constraints across clusters. Then, we propose to relax it into a chance constrained problem and solve it through sampled convex program. The relaxation is intended to eliminate the interdependence between clusters embodied by the constraints, so that a large RCS can be decomposed into independent linear sub-problems. Numerical experiments on unordered Internet image sets and sequential SLAM image sets, as well as distributed experiments on large-scale datasets, have demonstrated the high efficiency and scalability of the proposed approach. Codes are released at https://github.com/zlthinker/STBA.