Using ceftazidime mother liquor as the raw material, we recovered its effective components using suspension freeze concentration technology. Based on single factor test data, taking the recovery rate of ceftazidime as the evaluation index, we used the Box-Behnken response surface method to analyze the three extraction conditions of freezing temperature, freezing time, and stirring rate in three levels respectively to optimize the extraction conditions. The optimum recovery conditions of ceftazidime were as follows: freezing temperature -7 ℃, freezing time 3 h, stirring rate 20 r/min. Results show that the recovery of ceftazidime under these conditions was 93.15%.Combined with the actual production situation, the optimized suspension freeze concentration process is stable and can shed light on the follow-up study of ceftazidime.

To describe the deformation process of saturated soil, a consolidation drainage triaxial compression test was performed with saturated soil of a slope as the research object. The stress-strain curve of saturated soil was found to be approximately hyperbolic.Thus, Duncan-Chang model was chosen as the basic model, and a new modified model of Duncan-Chang model was constructed based on statistical damage theory. Through Duncan-Chang model′s own characteristics and linear regression method, the model parameters were solved. The test data of saturated soil is identified using the built model, as well as the test and theoretical curves, were compared and analyzed. Results showed that the modified model has a simple structure and fewer parameters and can accurately identify the deviatoric stress-strain curve of saturated soil.

In this study, a quantitative proton nuclear magnetic resonance (qHNMR) method was proposed to determine the deuteration rate of iodomethane-d3.An experiment was conducted on a 400 MHz spectrometer using dimethyl terephthalate (DMT) and dimethyl sulfoxide (DMSO-d₆) as the internal standard reference and deuterated solvent, respectively. The following parameters were set: spectral width 4807.69 Hz, transmitter frequency offset 2000.65 Hz, relaxation delay time 65 s, and number of scans 16 times. The peak of δ2.16 in iodomethane-d2 and that of δ8.07 in dimethyl terephthalate were considered as the quantitative and internal standard peaks, respectively. The methodological assessment of linearity, precision, repeatability, stability, and durability was performed, and good results were achieved. The proposed qHNMR method can be used for determining the deuteration rate of iodomethane-d3. This method is accurate, reliable, simple, and fast and does not require its own reference substance. Thus, it can meet the test requirements of iodomethane-d3 deuteration rate in the laboratory.

In this paper, the size (the number of vertices) of larger connected components of 3-ary n-cubes with fault edges are obtained, and then it is proved that a 3-ary n-cube is (4n-6)-strong Menger edge connected under conditional edge faults. Finally, a counter example is given to show that the result is optimal.

In this study, to reduce the impact of non-measureable noise on the measurement accuracy and to improve the monitoring accuracy of an engineering structure′s dynamic deformation in digital photography, the standard Kalman filter, variance-compensated Kalman filter, maximum posterior Kalman filter, and variance component Kalman filter are used to deal with the bridge elastic large deformation data; the Kalman filtering adaptability in dealing with dynamic deformation data is studied; and the advantages of employing variance component Kalman filter in data processing are quantified. It is found that the noise processing of variance component Kalman filter is stable and the error is small. This method is suitable for the processing of dynamic elastic small deformation noise in digital photography and exhibits good results in the processing of dynamic elastic large deformation noise in digital photography. Laboratory experiments on similar materials show that after data processing via variance component Kalman filter, the measurement error is less than 0.5 mm, which meets the accuracy requirement of deformation monitoring.

Polar code is the only linear error-correcting channel code that has been proved theoretically to reach the Shannon Limit. Herein, on the basis of the existing studies on the second and third-order kernel matrices of polar codes, the construction criteria of an optimal fourth-order kernel matrix are proposed: the main diagonals are 1, the number of “1” in the last line is 4, and all the matrices conforming to the abovementioned criteria are determined. Unlike the second-order kernel matrix, which only exhibits a single linear form, the fourth-order kernel matrix can take several forms, providing the polarization codes with more options in the construction. Then, taking the kernel matrix as an example, the channel polarization principle is introduced in detail. Finally, the steps for constructing a polar code having a specific block length with a given kernel matrix of any dimension are summarized.

Aiming at the problems of BI-RRT algorithm in path planning, such as poor target orientation, slow convergence speed, and numerous inflection points, an improved BI-RRT algorithm is proposed in this paper. The random tree is guided to grow faster toward the target point through target orientation to accelerate the convergence speed. In addition, the introduction of greedy path optimization strategy effectively reduces the path inflection points and improves the efficiency of path planning algorithm. Furthermore, a disk collision detection algorithm is also proposed. Path planning simulation experiments on a disk mobile robot is performed in several scenarios using Matlab. The feasibility and effectiveness of the proposed algorithm are verified via experimental results.

In this paper, we propose a trajectory tracking control law based on backstepping approach for the SCARA robot. We design the virtual and actual control terms by employing the backstepping approach. Based on Lyapunov's stability theory, the designed control law can track the trajectory of the robot and ensure that the closed-loop system is globally stable. Simulation results verified the effectiveness of the designed algorithm. The closed-loop system is uniformly globally asymptotically stable,which effectively improves the accuracy performance of trajectory tracking and ensures the convergence of the tracking error signal.

Currently,a large number of human errors exist in the packaging line for automobile brake discs, which restricts the efficiency of a automobile brake disc packaging system. This study developed an integrated, efficient and intelligent system. Siemens PLC was used as the lower computer of the system, WinCC configuration software was used for the upper computer, and web publishing was implemented through WinCC Web Navigator. This system has a user-friendly human-machine interface and comprehensive functions, which can meet the requirements of brake disc automatic packaging, improve work efficiency and packaging quality, and save labor costs.

The biomechanical environment of bone marrow mesenchymal stem cells (BMSCs) in vivo is relatively complex. To explore the relationship between biomechanics and the proliferation and osteogenic differentiation of BMSC, This review summarizes the current research status and latest progress of the effects of biomechanical microenvironment on the proliferation and differentiation of bone marrow mesenchymal sterm cells in recent years.Results showed that mechanical tension stress and fluid shear stress on BMSCs generated most of the stimuli to direct cell differentiation and that larger compression force and static water pressure on BMSCs generated most of the stimuli to direct cells toward cartilage differentiation and a minority of cells toward osteogenic differentiation. Cell differentiation in each direction occurred under its optimal conditions. Here we reviewed the effects of biomechanics on proliferation and osteogenic differentiation of BMSC, which may provide insights and references for research on bone tissue engineering, regenerative medicine, and clinical applications of BMSCs.

With calcium gluconate as the research object, a vacuum cooling crystallization experiment was performed to investigate the effects of time, temperature, stirring speed, and vacuum degree on the vacuum cooling crystallization of calcium gluconate. Results show that the factors affecting the crystallization rate of calcium gluconate are listed in the order of desceding degree of impact as vacuum degree, crystallization temperature, and stirring speed, among which the vacuum degree is a significant factor with P<0.05. The optimal process conditions for vacuum cooling crystallization of calcium gluconate are as follows: crystallization temperature is 50 °C, vacuum degree is 0.095 MPa, and stirring speed is 100 r/min. These results provide theoretical basis for technology and device development of calcium gluconate vacuum flash continuous evaporation crystallization.

To solve the problem of low efficiency of inspection of transmission line equipment, this paper designs a real-time inspection system for transmission line equipment based on Jetson-TX2. The main control module of Jetson-TX2 based on YOLO v3 and a Pan/Tilt/Zoom(PTZ) camera control module are included in this system. The YOLO v3 algorithm model is accelerated by TensorRT, which is transplanted in Jetson-TX2 to complete the real-time identification and positioning of the device target in the video stream. The PTZ camera is controlled by Jetson-TX2 to realize the high-definition image acquisition of the device through the PID algorithm. The system's overall recognition accuracy for transmission line equipment can reach 95%, which can realize real-time video detection. It can effectively improve the efficiency of transmission line inspection.

For the case in which the original model has the same weight at each reference point on a TV model, the paper propose a new concept whereby a diffusion function based on the gradient value of the pixels in the area to be repaired is constructed. The diffusion function is used to control the value of the contribution of each reference point. In addition, an adaptive iterative function for time parameters based on the idea of nonlinear diffusion is proposed. The diffusion function and adaptive iterative function work together to complete the image inpainting. Results of the experiment reveal that the new method proposed in this paper can achieve good processing effect in less time.

To prepare vitamin B₁₂ and to determine the optimal process parameters for the solvent-free crystallization technique, the purity and yield of the product were evaluated to optimize this technique using response surface methodology. The optimal process parameters were obtained as follows: evaporation temperature of 65 ℃, vacuum degree of 0.09 kPa, and concentration of 90 000 μg/mL prior to crystallization. It was shown that the solvent-free crystalization technique has high feasibility and effectiveness as the yield and quality of the final product were on par with that of solvent crystalization, if not better. While improving the safety of production, this technique cuts down pollution and eliminates certain procedures, thereby reducing the production cost and making it a good candidate for implementation in large-scale production.

To describe the creep mechanical behavior of rocks, triaxial compression creep tests of sandstone under different confining pressures are conducted herein. Results show that the steady creep stage is a process of developing and expanding microcracks in rocks, and the steady creep rate and confining pressure increase the power function. The long-term strengths of sandstone under confining pressures of 5 MPa, 10 MPa, and 15 MPa are 19.8 MPa, 22.3 MPa, and 24.7 MPa, respectively. The long-term strength increases with the increase in confining pressure. Based on the nonlinear characteristics of rock creep, the viscoelastic modulus E（p） associated with confining pressure is defined. E（p，t） that can reflect the influence of rock creep by time and confining pressure is obtained using the derivation transformation, which is applied to the improved Burgers model to obtain a new one-dimensional creep constitutive model. It can be extended to three-dimensional stress state to obtain a new three-dimensional nonlinear mechanical model, identify creep test data, compare and analyze the prediction results, and prove the feasibility and rationality of the model. The research results shed light on the simulation of creep behavior of rock under three-dimensional stress state.

By creating a special operator, the impulsive problem is transformed into a continuity problem. Then, we use the fixed point theorem of cone expansion and compression to investigate the boundary value problem of a second-order nonlinear impulsive differential system. Consequently, we confirm the existence of multiple positive solutions.

6-chloroimidazo[1,2-b]pyrazine-3-carbonitrile is a major intermediate of BMS-986260, which is a novel TGF-β R1 inhibitor that can be used as an anticancer drug. The synthesis goes through the following five-step reaction process with a total yield of 69.4%: hydrazine hydrate and maleic anhydride are considered as raw materials, acid-catalyzed condensation reaction, chlorination with phosphorus oxychloride, ammonolysis with ammonia water, imidization with N,N-dimethylformamide dimethyl acetal, and ring-closing condensation with bromoacetonitrile. The purity of the obtained product was 98.3%, which was measured via high-performance liquid chromatography (HPLC) at wavelength of 254 nm. The structure was confirmed through ¹H NMR and ¹³C NMR. Compared with the reported synthetic routes, this route exhibits good chemical selectivity, low cost, easy operation, and high yield. Further, it requires no column chromatography separation and is suitable for industrial production.

Aiming at the production characteristics and processing mode of crane main beam, a control system of crane main beam processing equipment based on PLC(programmable logic controller) was developed. The hardware composition and software design of the control system and the processing flow of the crane main beam processing equipment were introduced, and the PLC program of each control part was compiled according to the mechanic flow. The designed processing system realizes the automatic production of crane main beam, and it can process a single-section crane girder with a length of 6 m at one time, work efficiency was improved greatly. The practice shows that the system works stably, has high reliability and has practical value in engineering.

The determination of urban rainstorm intensity and rainstorm pattern serves as the basis for scientific planning and rational design of urban drainage systems. Based on the detailed precipitation data from Jinan National Basic Weather Station for 1961—2017, this paper studied the characteristics of short-duration rainstorm intensity and rain pattern change in four different periods using probability distribution model, Chicago method, and co-frequency method: 1961—1990, 1971—2000, 1981—2010, and 1991—2017. The results showed that Jinan′s short-duration rainstorm had been increasing intensity since the 1980s, and this is especially obvious since the 1990s. The short-duration and long-duration strong precipitation were all mainly concentrated in the first half of the precipitation process and had a tendency to postpone. This paper suggests that the local rainstorm intensity formula should be revised every 10 years or when the change rate of the rainstorm intensity exceeds 5%.

The crustose Trypethelium Lichen belongs to the Trypetheliaceae family, which is the second most diverse family among corticolous lichens after Graphidaceae. At present, there is no systematic study on this genus in China. Herein, we revealed the phylogenetic relationships of lichens of the genus Trypethelium by processing the samples collected from Guangdong, amplifying their ITS and LSU sequences, and constructing phylogenetic trees of the species. We also provided relevant descriptions and discussions of the reported species in China, as well as their taxonomic key.

We study the attractiveness of solutions for a Katugampola fractional differential equation. Using the Schauder fixed point theorem and measuring the noncompactness, we obtain the solutions for the Katugampola fractional differential equation and establish sufficient conditions for globally attractive solutions to the problem. Our results essentially reveal the characteristics of solutions for the Katugampola fractional differential equation.

In this paper, we study partially approximate controllability of Sobolev-type Hilfer fractional evolution equations with nonlocal conditions in Hilbert spaces. Using variational approach and approximating method， we provide the approximate solution operator of the control system and obtain the compactness of the approximate solution set. The sufficient conditions for the partially approximate controllability of the control system are obtained when Lipschitz conditions for the nonlocal function are not met.

The current problems of multiple interference factors and slow response time in online detection of low-volume-fraction SO2 gas in flue gas detection.In this case,an online SO₂ detection system based on the non-dispersive infrared absorption principle was designed,which used the characteristic capability of SO₂ to absorb infrared light in a specific band and adopted a single light source and dual channel method. Experiment results show that the zero drift is 0.4%, the response time is 3.86 s, the linear error is 0.3%, and the repeatability error is 0.52%. A comparison of parameters shows that this method can accurately measure SO2 concentration and is more suitable for the current demand of online flue gas detection.

This study investigated the interconnection bar and aluminum frame structure used in the packaging materials of photovoltaic modules to reduce the problem of hidden cracks in the failure of photovoltaic modules. By analyzing the reasons of hidden cracks in photovoltaic modules, a scheme to reduce the hidden cracks of photovoltaic modules under external force was proposed. The influence of the photovoltaic modules on the hidden crack was experimentally studied with different tensile ratio of the interconnecting bar,with or without the bending of the interconnecting bar and with or without the beam on the aluminum frame. Experiments revealed that setting reasonable tensile ratio of the interconnecting bar, bending degree of interconnecting bar, aluminum frame, and crossbeam, among other measures, could help in reducing the percentage of hidden cracks of photovoltaic modules and improve the reliability of photovoltaic modules. 

To solve the unsteady convection diffusion equation, we propose a new second-order algorithm that applies the multi-quadrics localized radial basis function(MQ-RBF-FD)method and dimension-splitting method for spatial discretization, and BDF2 methods and alternating iterative schemes for temporal discretization. We determine the appropriate number of iterations, choose an optimal shape parameter c, and finally, obtain higher order accuracy. We conducted numerical experiments to verify the rationality and feasibility of the theoretical results. 

To quantitatively study the inhibitory effect of anions on DNA condensation and charge neutralization, the effect of anions of various valencies on cation-mediated DNA condensation was studied using dynamic light scattering and atomic force microscopy (ATM). Dynamic light scattering experiments showed that anions reduced the electrophoretic mobility of DNA in the presence of cations, indicating that charge neutralization of DNA was inhibited. The higher valence of anions, the stronger was the inhibition of electrophoretic mobility. Different anions exerted the same inhibitory effect and trend on DNA charge neutralization at the same concentration of various cations. Meanwhile, the morphological changes in DNA condensation as observed by AFM led to the same conclusion. At the same cation concentration, highvalent cations showed more potent inhibition on DNA condensation than lowvalent cations, which make the DNA aggregation morphology more loose. These observations further confirmed that anions have a weakening effect on cationmediated DNA condensation.

The purpose of the cyber range based on the training environment in colleges and universities is to help students understand the business security needs by simulating the enterprise application scenarios, and promote the continuous improvement of students′ security skills through collect and evaluate the learning and training data on the platform in real time. In this paper, demand analysis and preliminary architecture design of the cyber range used in teaching units are carried out, and three dimensions in learning and training of a campus cyber range are proposed, which is practice module based on basic class knowledge, user-defined rate of progress of security challenge, dynamic practice based on team, respectively. Cyber range training are jointly driven by the three dimensions to cultivate the security professional  in a more comprehensive manner.

A method was established for the determination of genotoxic impurity.in erlotinib hydrochloride(3-ethynylaniline) using liquid chromatography-mass spectrometry. Using the ESI ion source positive ion multireaction monitoring (MRM) mode,the ion pairs 118→75 and 118→91 were selected and measured. The chromatographic column was Thermo Hyperiil GOLD C8(100 mm×4.6 mm,3 μm),the mobile phase was methanol and waterfor gradient elution,the flow rate was 0.4 mL/min,and the column temperature is 35℃.Results showed that the detection mass concentration of 3-ethynylaniline in this method had a good linear relationship in the range of 1.0 to 20 ng/mL, with R²=0.999 4.The relative standard deviation(n=6) of the precision experiment was 1.13%,and the recoveries of standard additions (n=3) at low,medium,and high concentrations were between 90.1% and 106.1%.The method exhibited high sensitivity,specificity,and precision,and it met the requirement for the determination of 3-acetyleniline,a genotoxic impurity in erlotinib hydrochloride tablets.

A microsample pH meter was prepared by modifying Iridium oxide thin film on a microelectrode using an electrochemical method. In the measurement process, the potential difference between the test and reference electrode was determined by dropping only approximately 3~5 μL solution on the electrode which with small volume. Then, data was obtained using a data acquisition card. The potential difference signal is converted into a digital signal, and the pH value is output with the Matlab software fitting curve. The measurement results of microsample pH meter are consistent with those of commercial pH meters. The electrode is convenient,and high sensitivity and good reproducibility, and it has superiority in the analysis of rare and expensive samples biological samples. Therefore, it has broad development prospects.

Most studies of convection-diffusion equation are in the range of constant coefficient or integer order. To more accurately describe the solute movement features, the traditional integer order convection-diffusion equation is extended to cases of fractional order variable coefficient. The paper primarily investigated the finite difference decomposition method of Caputo fractional order convection-diffusion equation with variable coefficients. This paper introduced a half integer point, performed dual partitioning on the spatial grid,and then discretized the spatial derivatives using the finite difference method. Theoretical analysis shows that the solution of the discrete format proposed in this paper exists and is unique, with a convergence accuracy of ο(τ+h).The accuracy of theoretical analysis is verified using one-dimensional numerical examples.

Using fixed point theorem of Banach, this paper discussed the existence and uniqueness of positive solutions for integro-differential equations on the infinite interval wherein the boundary conditions are non-negative constant. Furthermore, the dependence of positive solutions on boundary values was discussed as well.

Identification of a bryoflora specimen collected from Mount Tai lead to the report on Tortula raucopapillosa (X. J. Li) R. H. Zander as an addition to the bryoflora of Shandong Province, China. Detailed descriptions and an ink drawing of the  characteristics of this species are provided, whereas brief discussions and a key to the species of Tortula Hedw，and its related genus Syntrichia Brid. in Shandong Province are provided. 

On-line fault location distance measurement is very important for fault detection and repair of urban 10 kV cable lines. Because of the complex structure of distribution lines, the existing single-terminal or double-terminal traveling wave location technology for measuring distance cannot be directly appliedIt is impossible to locate the fault point accurately, check and repair it quickly, which brings certain inconvenience and economic loss to residents′ life and enterprise production. In this study, the characteristics of voltage and current traveling wave and the refraction and reflection laws in a typical 10 kV cable network are analyzed when grounding fault occurs, particularly in the ring cabinet and at the end of the line.This paper presents the system structure and working principle of a distributed fault traveling wave ranging system installed in the ring network cabinet and the end of the line, as well as the key technologies such as high-speed data acquisition, sensor acquisition frequency band selection and the end of the line current traveling wave acquisition method,The reliability and accuracy of the technology and system are verified using several field examples.

This paper proposes a text-feature extraction method based on a convolutional recurrent neural network, and in the meanwhile, it also compares the statistical methods TF-IDF and Word2vec for text-feature representation. Text features are then fed into the SVM and Random forest classifier to classify the Chinese academic papers from CNKI. Experimental results show that the classification results obtained from the feature extraction models based on the convolutional neural network and convolutional recurrent neural network are better than those obtained from the TF-IDF and Word2vec feature extraction methods. Furthermore, the classification results obtained from the SVM and Random forest classifier are slightly better than those obtained from the native neural network

In this study, a new representation of the Drazin inverse of the sum of two matrices is provided under certain conditions based on the definition of the Drazin inverse, the matrix decomposition philosophy, and the usage of the related properties of the Drazin inverse. This new result is an expansion of some of the existing results.

In this study, the effect of divalent counterions on the conformational change of the semi-flexible polyelectrolyte chains was investigated at different pH based on Langevin’s dynamics. Polyelectrolyte is represented by a coarse-grained bead spring model, with the radius of gyration (Rg) remaining almost constant at pH-pK>0. Rg reduces and the polyelectrolyte chain shrinks as the value of pH-pK decreases. Meanwhile, in the experiment, the atomic force microscopy images of the DNA mediated by Mg²⁺ were obtained in different pH environments to denote that the DNA remained in a free and loose state in neutral and weakly acidic environments. At pH<4, i.e., strong acidity, DNA was gradually condensed into a spherical shape and stabilized. Further, the experimental result agrees with the simulation results.

In this study,an integrated design method that combines the sensor and processor is proposed to overcome the disadvantages of the traditional flame detector,including easy attenuation and interference as well as short transmission distance.The proposed design method improves the reliability of the entire machine in a complex environment.Based on the analysis of the ultraviolet photoelectric flame detection working principle,the project judges the existence of a flame by detecting the ultraviolet pulse number and intensity of the flame signal.Further,methods for circuit and software design,such as high-voltage driving,flame-state signal transmission,and flame signal processing,are proposed in this study.The detector is observed to be of excellent practical value in the field of gas combustion furnace based on the field test results obtained using a gas combustion furnace.

A robot may employ different techniques and control methods based on system requirements. Robot operating system (ROS) is a widely used open source software architecture platform for robot control. In this study, a mobile robot control architecture is designed based on the ros_control implementation mechanism. Using different parameters in configuration files and customized hardware interface protocols, the differential drive control of mobile robots can be adjusted to suit different hardware configurations.

In response to the problems that are associated with the production of brake pad stamping, we propose the usage of a robot instead of manual operation to automatically load and unload materials during brake pad stamping. The overall design of feeding robot was conducted in accordance with the stamping process of the brake pad and the feeding requirements. A three-dimensional robot model was designed using SolidWorks, and the kinematic equations of the robot were established using the D-H displacement matrix method. The simulation analysis of robot motion was performed using the ADAMS software, indicating that the data with respect to the trajectory, pose, and joint velocity of the endpoint were obtained and verifying the design accuracy.

In this study,the drying process and characteristics of Penaeus vannamei are studied under different pretreatments using water steaming and soaking.Further,the effects of the pretreatment methods on the quality of the dried products are studied based on their hardness,elasticity,and rehydration rate.The experimental results denote that the water content of Penaeus vannamei obtained using different pretreatments vary;further,the initial moisture content of Penaeus vannamei and loss of dry matter after steaming is lower than those after boiling.The drying process of Penaeus vannamei only undergoes the falling drying rate stage,and water diffusion plays a dominating role.The quality of the dry products can be improved by conducting pretreatment before drying.When compared with the product obtained using the boiled pretreatment method,the dried product obtained after conducting steam pretreatment exhibits a higher rehydration rate,brighter color,and tighter and more elastic muscle tissue.