Combined Test Method Research Articles

Flow behaviors of various metals under tensile load

Abstract The influence of flow behaviors on the results of finite element (FE) analyses of metal-forming processes is dominant, even though it varies with strain hardening and softening phenomena. However, obtaining a flow curve with sufficient accuracy is not easy, particularly at large strains. Among various well-known methods of obtaining flow curves, tensile testing-based method is effective to obtain flow curves at large strains at room temperature. It is believed that the strain hardening behavior at large strains during the tensile test was not fully known. In this study, the flow curves, previously obtained using the combined tensile test and finite element method (FEM) approach, are classified as four categories, including monotonic strain hardening function, double-curvature strain hardening function, strain hardening-perfectly-plastic function, and perfectly-plastic-strain softening function. The tensile test characteristics of each type are investigated using its FE predictions, revealing that the specific type of a material can be identified by the tensile test.

花生清选筛台架的设计与试验

In order to address the high impurity and loss rates in the cleaning process of existing peanut combine harvesters, the design basis of the cleaning sieve was explored. Tests were conducted to determine the composition of the peanut picking fruit and the characteristics of the material suspension mixture. Additionally, the mechanical relationship between the fruit and miscellaneous mixtures and the cleaning sieve was investigated. The wind speed ranged from 8 m/s to 10 m/s, the vibration frequency ranged from 6 Hz to 8 Hz, and the inclination angle of the sieve ranged from 5° to 9°. The scavenger sieve platform was constructed and tested using Box-Behnken’s central combination test method. The optimal combination of fan wind speed (9 m/s), sieve surface inclination angle (8°), and sieve vibration frequency (7 Hz) resulted in a pod impurity rate of 1.16% and a loss rate of 1.4%. The device significantly reduces impurity content and loss rate during peanut harvesting. The study's results can serve as a reference for improving the design of the peanut combine harvester cleaning mechanism and optimizing operating parameters.

粮食干燥机自吸式热风变温装置设计与试验验证

During the grain drying process, in order to adjust the temperature, it is necessary to match the proportion of hot and cold air. This is the problem that the two components in the mixed gas cannot fully mix with each other in a short period of time, resulting in the problem that it takes a long time for the gas flow temperature to reach a stable value. Based on the process and technical requirements of the dryer, a self-priming hot air temperature changing device suitable for the dryer was designed. The two gas components used to improve the variable temperature ratio of the dryer are fully mixed with each other in a short time and a short distance, thereby reducing the loss caused by the food not reaching safe moisture. Based on Bernoulli's principle and the basic theory of airflow mixing in fluid dynamics, a mathematical model of airflow mixing in the constriction section of the main pipeline was established. Fluent was used to numerically simulate the distribution of uniform mixing distance and temperature field in the necking section. The results show that the mixing uniformity in the necking section reaches 75%-80%, which effectively improves the mixing efficiency. A self-priming hot air temperature change device test bench developed independently was used, and the quadratic orthogonal rotation combined test method was used for parameter optimization. Design-Expert.V8.0.6.1 was used for analysis and testing, and the regression equation and response surface were obtained to analyze the effects. Interaction between factors to determine the best combination of optimization parameters: when the number of air inlet pipes is 3.16, the incision axial angle is 27.6°, the temperature difference is 43.5°C, and the pipe diameter is 23.8mm, the post-mixing temperature is 50.93°C, and the mixing distance is uniform is 39.33mm. The test results are consistent with the optimization results. The self-priming hot air temperature changing device of the dryer has certain practical application value.

Camera-in-the-loop based test scenario generation method for pedestrian collision avoidance system

The Pedestrian Collision Avoidance System (PCAS) of Intelligent Vehicle (IV) can be effective in preventing the occurrence of traffic accidents. However, the complicated operation environments introduce great challenges to the camera used by the PCAS. Therefore, the camera based PCAS should be fully tested and evaluated before deployment. The traditional simulation test for the camera based PCAS attempted to use geometric or physical simulation models, which have low reality and are suitable for the primary stage of the PCAS development. Camera-in-the-Loop (CIL) test is one of Hardware-in-the-Loop methods that embeds the real camera hardware into the virtual simulation system to test the camera. CIL can utilize the real hardware response while overcoming the common simulation weakness of fidelity. In this paper, we construct a CIL test platform, and propose the CIL based test scenarios generation and scenario parameter impact evaluation method for PCAS. First, we construct the CIL test platform whose image quality and functional confidence are both validated to prove CIL credibility. Second, the PCAS under the test is analyzed and the corresponding test scenario parameters are designed. In order to accelerate the test scenario generation, a Greedy Based Combination test method (GBC) based on the CIL is proposed. The Chi-square analysis and two-factor of variance analysis verification methods are used to analyze the influence of individual and multiple scenario parameters on the PCAS performance. The experiment results show that the GBC improves the test speed by 12 times compared to the traversal test, and the frequency ratio of each scenario parameter is no more than 3% different from that of the traversal test. Also, GBC has an equivalent ability to find the PCAS collision scenarios parameter combination to the traversal test.

Prevalence of metallo-beta-lactamase in clinical isolates of Pseudomonas aeruginosa and Proteus mirabilis in Benin City, Nigeria

Carbapenems are the prime choice of treatment for severe cases of infections caused by Multi-Drug-Resistant Pseudomonas aeruginosa and Proteus mirabilis. Nevertheless, Metallo-Beta-Lactamase (MBL) production by these organisms has led to carbapenem resistance which is a global threat. This study aimed to determine the prevalence and antimicrobial susceptibility profile of MBL in clinical isolates of Pseudomonas aeruginosa and Proteus mirabilis in Benin City, Nigeria. 354 non monotonous clinical isolates of Pseudomonas aeruginosa (282) and Proteus mirabilis (72) used were obtained from various clinical samples from tertiary hospitals in Benin City. Identification of these isolates were done using standard microbiological techniques. Antimicrobial susceptibility test was performed using Kirby-Bauer disk diffusion method. MBL production was detected using Imipenem Ethylene-Diamine-Tetra-Acetic Acid combined disc test method. Of the total 354 clinical isolates tested, 115 (32.48%) were MBL and the prevalence of this resistant isolates was significantly higher in Pseudomonas aeruginosa (46.8%) compared to Proteus mirabilis (P=0.0001). Among the metallo-beta-lactamase producing isolates of Pseudomonas aeruginosa higher prevalence were reported from Pleural fluid and cerebrospinal fluid samples with 6 (100%) and 3 (100%) respectively. This difference was statistically significant (P=0.0001). Susceptibility testing showed that isolates that produced beta-lactamase demonstrated poorly against cephalosporin, amoxicillin-clavulanate, gentamicin and floroquinones than non-beta- lactamase producers. A prevalence of 46.8% was reported for MBL producing Pseudomonas aeruginosa and 12.5% was reported for MBL producing Proteus mirabilis. Isolates that produced the MBL enzyme were more resistant to antibacterial agents. Measures to control and curb the spread of MBL producing clinical isolates are highly advocated

Fabrication, Modeling, and Testing of a Prototype Thermal Energy Storage Containment

Abstract Increasing penetration of variable renewable energy resources requires the deployment of energy storage at a range of durations. Long-duration energy storage (LDES) technologies will fulfill the need to firm variable renewable energy resource output year round; lithium-ion batteries are uneconomical at these durations. Thermal energy storage (TES) is one promising technology for LDES applications because of its siting flexibility and ease of scaling. Particle-based TES systems use low-cost solid particles that have higher temperature limits than the molten salts used in traditional concentrated solar power systems. A key component in particle-based TES systems is the containment silo for the high-temperature (>1100 ∘C) particles. This study combined experimental testing and computational modeling methods to design and characterize the performance of a particle containment silo for LDES applications. A laboratory-scale silo prototype was built and validated the congruent transient finite element analysis (FEA) model. The performance of a commercial-scale silo was then characterized using the validated model. The commercial-scale model predicted a storage efficiency above 95% after 5 days of storage with a design storage temperature of 1200 ∘C. Insulation material and concrete temperature limits were considered as well. The validation of the methodology means the FEA model can simulate a range of scenarios for future applications. This work supports the development of a promising LDES technology with implications for grid-scale electrical energy storage, but also for thermal energy storage for industrial process heating applications.

Generalization of cut-in pre-crash scenarios for autonomous vehicles based on accident data

The utilization of high-risk test cases constitutes an effective approach to enhance the safety testing of autonomous vehicles (AVs) and enhance their efficiency. This research paper presents a derivation of 2052 high-hazard pre-crash scenarios for testing autonomous driving, which were based on 23 high-hazard cut-in accident scenarios from the National Automobile Accident In-Depth Investigation System (NAIS) through combining importance sampling and combined testing methods. Compared to the direct combination of the original distribution after sampling, the proposed method has a 2.92 times higher crash rate of 69.32% for the test case set in this paper. It also has a 5.8 times higher rate of triggering Automatic Emergency Braking (AEB), improving hazardous scenario coverage. Using the proposed method, the generated parameters of the cut-in accident scenario test set were compared with those of the cut-in test scenarios included in existing Chinese autonomous driving test protocols and standards. The velocity of the ego-vehicle obtained using the proposed method matched those in the existing protocols, whereas the velocity, time gap, and time to collision of the target vehicle were significantly lower than those existing protocols indicating scenarios obtained from accident data can enrich the selection of testing scenarios for autonomous driving.

Computational and Experimental Characterization of Aligned Collagen across Varied Crosslinking Degrees.

Collagen-based scaffolds have been widely used in tissue engineering. The alignment of collagen fibers and the degree of crosslinking in engineering tissue scaffolds significantly affect cell activity and scaffold stability. Changes in microarchitecture and crosslinking degree also impact the mechanical properties of collagen scaffolds. A clear understanding of the effects of collagen alignment and crosslinking degrees can help properly control these critical parameters for fabricating collagen scaffolds with desired mechanical properties. In this study, combined uniaxial mechanical testing and finite element method (FEM) were used to quantify the effects of fiber alignment and crosslinking degree on the mechanical properties of collagen threads. We have fabricated electrochemically aligned collagen (ELAC) and compared it with randomly distributed collagen at varying crosslinking degrees, which depend on genipin concentrations of 0.1% or 2% for crosslinking durations of 1, 4, and 24 h. Our results indicate that aligned collagen fibers and higher crosslinking degree contribute to a larger Young's modulus. Specifically, aligned fiber structure, compared to random collagen, significantly increases Young's modulus by 112.7% at a 25% crosslinking degree (0.1% (4 h), i.e., 0.1% genipin concentration with a crosslinking duration of 4 h). Moreover, the ELAC Young's modulus increased by 90.3% as the crosslinking degree doubled by changing the genipin concentration from 0.1% to 2% with the same 4 h crosslinking duration. Furthermore, verified computational models can predict mechanical properties based on specific crosslinking degrees and fiber alignments, which facilitate the controlled fabrication of collagen threads. This combined experimental and computational approach provides a systematic understanding of the interplay among fiber alignment, crosslinking parameters, and mechanical performance of collagen scaffolds. This work will enable the precise fabrication of collagen threads for desired tissue engineering performance, potentially advancing tissue engineering applications.

Virtual parameter calibration of pod pepper seeds based on discrete element simulation

In order to achieve numerical optimization of the pod pepper seed sowing device, the contact parameters of pod pepper seeds were calibrated, with the angle of repose used as the response value. A set of discrete element method (DEM) models of pod pepper seeds was developed to simulate the formation of seed repose angles using reverse engineering reconstruction techniques. An eight-factor, three-level response surface experiment based on the Box-Behnken central combination test method was performed to study the effects of various factors on the angle of repose of seeds. The angle of repose obtained from physical experiments with a value of 27.56° was taken as the target value. The optimal combination of parameters is obtained as follows: seed Poisson's ratio of 0.22, seed shear modulus of 15.47 MPa, seed-to-seed static friction coefficient of 0.25, seed-to-seed rolling friction coefficient of 0.67, seed-to-seed collision recovery coefficient of 0.64, seed-to-steel-plate static friction coefficient of 0.55, seed-to-steel-plate rolling friction coefficient of 0.45, and seed-to-steel plate collision recovery coefficient of 0.34. A two-sample t-test of the angle of repose obtained by the cylinder lifting method and the pumping plate method against the target value yielded P > 0.05, indicating the reliability of the simulation experiments.

Characterization of Sand and Dust Pollution Degradation Based on Sensitive Structure of Microelectromechanical System Flow Sensor.

The effect of sand and dust pollution on the sensitive structures of flow sensors in microelectromechanical systems (MEMS) is a hot issue in current MEMS reliability research. However, previous studies on sand and dust contamination have only searched for sensor accuracy degradation due to heat conduction in sand and dust cover and have yet to search for other failure-inducing factors. This paper aims to discover the other inducing factors for the accuracy failure of MEMS flow sensors under sand and dust pollution by using a combined model simulation and sample test method. The accuracy of a flow sensor is mainly reflected by the size of its thermistor, so in this study, the output value of the thermistor value was chosen as an electrical characterization parameter to verify the change in the sensor's accuracy side by side. The results show that after excluding the influence of heat conduction, when sand particles fall on the device, the mutual friction between the sand particles will produce an electrostatic current; through the principle of electrostatic dissipation into the thermistor, the principle of measurement leads to the resistance value becoming smaller, and when the sand dust is stationary for some time, the resistance value returns to the expected level. This finding provides theoretical guidance for finding failure-inducing factors in MEMS failure modes.

Design and Experiment of Active Spiral Pushing Straw Row-Sorting Device

Aiming to solve the problems of excessive straw residue and large soil loss in the seeding belt of the straw row-sorting operation when the full volume of straw is crushed and returned to the field in the northeastern region of China, an active spiral pushing straw row-sorting device (ASPSRD) was designed in this paper. The straw on the surface of the land is collected and stirred by the high-speed rotating spiral-notched blades in the device and pushed to the non-seeding area for the purpose of cleaning the seeding belt. The parameters of key components were determined through theoretical analysis. The orthogonal combination test method of four factors and three levels was adopted. The EDEM discrete element simulation experiment was carried out by selecting the straw mulching quantity (SMQ), the rotating speed of the active rotating shaft (RSARS), the forward speed of the tractor (FST), and the notch width of the spiral notch blade (NWSNB) as the test factors, and the straw-cleaning rate (SCR) and soil loss rate (SLR) as the test indexes. Through range analysis, the parameters were optimized, and the optimal operation parameters of the straw row-sorting device were determined as follows: SMQ was 1.8 kg/m2, RSARS was 120 rpm, FST was 4 m/s, and NWSNB was 9 mm. The operational performance of the device was verified by field experiments. The results of the test showed that after the device was operated with the optimal combination of parameters, the SCR of the 20 cm wide seeding belt was 95.32%, and the SLR was 7.12%, which met the agronomic and technical requirements of corn no-tillage sowing operation in Northeast China. This study can provide a reference for the design of a straw row-sorting device of a no-tillage machine.

Prevalence of extended-spectrum beta-lactamases producing isolates obtained from patients of pediatric critical care unit in a tertiary care hospital

Background: Over the past decades, antibiotic-resistant Gram-negative bacteria commonly Enterobacteriaceae such as Escherichia coli and Klebsiella pneumoniae have increased significantly. These microorganisms have great clinical importance because they increase hospital stay of the patients in the intensive care unit (ICU) leading to high morbidity and mortality. Because of their role in increasing morbidity and mortality, this study was performed to isolate extended-spectrum beta-lactamase (ESBL) producing Gram-negative bacilli screened by phenotypical method and further projected into molecular characterization by polymerase chain reaction. Aims and Objectives: The aims and objectives are to isolate the Gram-negative multidrug-resistant strains from clinically suspected bacterial infections in patients of neonatal, sick newborn, and pediatric ICU and to study antibiotic sensitivity pattern of isolated Gram-negative multidrug-resistant strains with special reference to molecular characterization. Materials and Methods: A total of 100 Gram-negative bacilli were isolated. Screening of ESBL positivity was done by double-disk synergy test (combined disc test method). Their antibiogram profile was interpreted. With the use of designed primers, 26 ESBL isolates each of E. coli and Klebsiella spp. were processed for molecular analysis of beta-lactamase family genes TEM and CTX-M. Results: Within the 100 samples, majority of the isolates (45%) were Klebsiella spp. and 40% was E. coli isolates. Highest ESBL-producing organisms were observed within E. coli (65%). Prevalence bla-TEM gene was highest followed by bla-CTX-M. These ESBL-producing organisms were found to be resistant to multiple classes of antibiotics. With extensive ESBL surveillance and proper usage of antibiotics, this threatening rise of antibiotic resistance can be mitigated. Conclusion: Gram-negative isolates showed high resistance to commonly used antibiotics. Significant proportions of them were MDR strains. Such high antibiotic resistance is associated with significant morbidity and mortality among pediatric population. MDR along with possession of ESBL associated resistance genes among Gram-negative bacilli pose a serious problem in therapeutic management of patients. Our study signifies that there is a high probability of Gram- negative bacilli to be multi-drug resistant and ESBL positive and earliest detection of such cases should be made.

Simulation and parameter optimization of high moisture rice drying on combine harvester before threshing

Aiming at the problems of conveying, threshing and cleaning devices blockage while harvesting the high moisture by combine harvester, the idea of reusing waste heat of combine harvester to dry rice on machine before threshing was put forward. The surface moisture of rice dried by hot air in cutting header was studied. The computational fluid dynamics (CFD) coupling discrete element method (DEM) simulation experiment based on the quadratic orthogonal rotating center combination test method was performed. The impact of feeding amount, hot air velocity, hot air temperature and initial water content of rice on the rice dehydrator rate was analyzed and the relationship model between them was built. The optimal solution for the rice drying was obtained using the relationship model. A test bench was set up to validate the accuracy of the model. The results demonstrate that each factor significantly influences the dehydration rate with their important order as follows: rice feeding quantity > rice initial moisture content > hot air temperature > hot air velocity; the optimal solution is rice feed quantity of 100 g, hot air velocity of 6 m/s, hot air temperature of 150 °C, initial moisture content of 20% and a maximum dehydrator rate of 1.541%; the validation test confirms that the acquired relationship model exhibits sufficient prediction accuracy with the maximum relative error of 8.5%.

Virulence And Drug Resistance Pattern Of Escherichia Coli Isolates From Various Clinical Sample

Introduction: E. coli is one of the most common pathogens, and its infection has resulted in a global burden due to its increased medication resistance and virulence factors. The goal of this study was to examine the drug resistance pattern and pathogenicity properties of Escherichia coli isolates. Methods: Over the course of six months (March 2019-August 2019), a laboratory-based cross-sectional study was done among patients visiting Manmohan Memorial Teaching Hospital in Kathmandu, Nepal. Standard microbiological procedures were used to identify bacterial isolates from clinical specimens. The modified Kirby Bauer disk diffusion method was used to determine antibiotic susceptibilities. The combined disk test method was used to confirm the ESBL and MBL. To determine their virulence, serum bactericidal activity and biofilm productions were determined. Results: 59.60 percent (n=81) of the 136 Escherichia coli isolates were multidrug resistant, 25.70 percent (n=35) were ESBL producers, and 11.80 percent (n=16) were MBL producers. Serum resistance was discovered in 22.8 percent (n=31) of the total isolates, while biofilm formation was found in 19.11 percent (n=26). Amoxycillin had the highest level of resistance (87.5%), whereas Chloramphenicol (93.4%) and Imipenem (80.9%) were the most susceptible antibiotics. Polymyxin B and Colistin sulphate were absolutely sensitive. In our investigation, 61.5 percent of biofilm producers were MDR, with non-beta lactamase types being the most common. MBL producers were discovered to be more serum resistant. Amikacin and Imipenem were found to be more sensitive to biofilm makers. Conclusions: The expression of Escherichia coli virulence factors varied depending on the kind of infection. Escherichia coli has a high rate of multidrug resistance. To minimize the emergence and spread of antibiotic resistance in bacteria, proper identification of drug-resistant bacteria, careful use of antibiotics, and effective antibiotic policy are required.

Mechanistic analysis and experimental study of a shear-type low-loss fresh corn ear-picking mechanism

Existing fresh corn (FC) ear-picking devices have a high ear damage rate and power consumption. To solve these problems, this paper proposes a shear-type ear-picking method that can reduce FC loss and power consumption. Using mechanical property tests for peduncles, the feasibility of the shear-type ear-picking mechanism was analyzed. According to the principle of contact mechanics, the factors influencing the contact force in shear-type ear picking were identified and a shear-type ear-picking mechanism with low FC loss was designed. By studying the relationship between the shear failure ratio of peduncles and the drawing force, the boundary conditions of ear picking without FC loss, and the interactions between plants and the ear-picking mechanism, a shear-type ear picking model without any loss using the combined quadratic regression orthogonal rotation test method was established. The mean shear failure ratio of peduncles was 73.97% by statistically analyzing the shear failure ratio of peduncles under different rotation speeds, which meets the boundary conditions of lossless ear picking. The results of the bench tests indicate that the shear failure ratio of peduncles was 72%, and the ear damage rate was 2.1%, satisfying the requirements of low FC loss under ear picking operations. Compared with the traditional board-type ear-picking mechanism, this method reduced the ear damage rate and power consumption by 8.6% and 15.5%, respectively. This study provides a theoretical foundation and technical reference for the development of FC harvesting equipment.

基于 EDEM 的双滚轮破碎装置优化设计

Straw found in the field can be conveniently stored and transported through mechanical packaging, and it undergoes crushing during its utilization. The effectiveness of the crushing process directly impacts the efficiency of material utilization. However, current crushing devices available in the market lack specialized mechanisms suitable for the unique characteristics of round corn stalks. To address this issue, the necessary simulation parameters were determined, and an experiment was conducted using the ternary quadratic combination test method. The test factors considered were the center height difference of the knife roller, lower roller speed, and cutter thickness. The response value of the experiment was the material crushing rate. By analyzing the results, the optimal structural parameters were identified. These included a center height difference of 390 mm for the knife roller, a lower roller speed of 14 rpm, and a cutter thickness of 110 mm. With these parameters, the crushing rate of the round straw crushing device reached 93.77%, and the particle passing ratio was 98.52%. To validate the research findings, a test device was constructed and used to confirm the reliability of the obtained results.

Optimization of Manufacturing Parameters and Experimental Study of Rice Straw Fiber-Based Plant Fiber Seedling Pots

In order to improve and alleviate environmental pollution caused by the disposal of seedling pots, a rice straw fiber-based headed vegetable seedling pot material, which is suitable for mechanical transplantation and biodegradable, was studied. Used rice straw as the main raw material, a five-factor and five-level (1/2 full implementation) quadratic regression orthogonal rotation central of rotation combination test method. The experimental factors included the beating degree of rice straw fiber, quantity, the proportion of rice fiber, neutral sizing agents, and wet strength agent mass fraction. The performance evaluation index included dry and wet tensile strength, burst strength, tear strength, air permeance, and degradation period. The results showed that when the parameter combination of the beating degree of rice straw fiber was 50 ± 1°SR, the quantity was 87.5 ± 4 g/m2, the proportion of fiber in rice was 70%, the neutral sizing agents mass fraction was 1 ± 0.25%, and the wet strength agent mass fraction was 1.5 ± 0.1%. The dry tensile strength was ≥ 1.8 kN·m−1, the wet tensile strength was ≥ 0.7 kN·m−1, the burst strength was ≥ 140 kPa, the tear strength was ≥ 350 m·N, the air permeance was ≤ 1.33 μm/Pa·s, and the degradation period was ≤ 80 d. The dry tensile strength reduction rate was 0.0274 kN/(m·d) and the wet tensile strength reduction rate was 0.0113 kN/(m·d), during the nursery period [30, 40], while the dry tensile strength was ≥ 1 kN·m−1 and the wet tensile strength was ≥ 0.4 kN·m−1 during the transplanting period.

Role of the score for the targeting of atrial fibrillation (STAF) combined with D-dimer in screening ischemic stroke patients with atrial fibrillation.

We aim to explore the effect of the score for the targeting of atrial fibrillation (STAF) combined with the serum D-dimer (DD) level in screening acute ischemic stroke patients with atrial fibrillation (AF). This study is a retrospective case observation study. This study consecutively selected patients with acute ischemic stroke who were hospitalized in the Department of Neurology at Zhuhai Hospital Affiliated with Jinan University from February 2019 to February 2021. Venous blood was drawn from all patients within 24 hours of hospitalization for DD detection. In accordance with the medical records, the patients were classified into an AF group and a non-AF group and were scored according to the STAF standard. A combined test method was used to estimate the diagnostic screening value of the STAF combined with the DD value for acute ischemic stroke patients with AF.

PREVALENCE RATE OF ESBL AMONG ENTEROBACTERIACEAE ISOLATED FROM UTI PATIENTS IN SULAIMANI PROVINCE

Background Extended-Spectrum β-Lactamase are enzymes that provide resistance against third-and fourth generation Cephalosporins and Monobactams, and they are distributed among the Enterobacteriaceae family.
 Objectives To describe the prevalence of Extended-Spectrum β-Lactamase among Enterobacteriaceae causing urinary tract infections in Sulaimani province.
 Patients and MethodsOne hundred bacterial isolates of Enterobacteriaceae from patients with urinary tract infections attending Smart Hospital (inpatients and outpatients). Urine samples were inoculated onto different culture media. Colony morphology, gram staining, and BD Phoenix™ system were used for bacterial identification. Antibiotic profile and Extended-Spectrum β-Lactamase were observed phenotypically by antibiotic profile results, double disk synergy test, and confirmed by combined disk test methods and BD Phoenix™ system.
 ResultsOut of one hundred isolates of Enterobacteriaceae, Escherichia coli was the commonest isolate (89), followed by Klebsiella pneumoniae (10) and one isolate of Proteus mirabilis. According to the antibiotic profile, the most effective antibiotic among all three isolates was Imipenem and Nitrofurantoin, while the most resistant antibiotic was Nalidixic acid and third generation Cephalosporin. The prevalence rate of Extended-Spectrum β-Lactamase -producing Enterobacteriaceae was 69% by the screening tests and 48% by the confirmatory tests.
 ConclusionIn this study, Extended-Spectrum β-Lactamase prevalence was shown to be at an alarming rate that must be considered. The high priority of public health justifies further investigation to properly establish annual surveillance systems that can aid in selecting an appropriate antibiotic upon ESBL detection.

Design and Test of a Straw-Clearing-Depth Self-Adaptive Control System of a Front-Mounted Seedbed-Preparation Device

In northeast China, most seedbed-preparation devices use the ground-wheel profiling method to ensure their operational stability. However, during the wide-width operation of the front-mounted seedbed-preparation device, the poor trafficability characteristics and the low profiling accuracy of the ground-wheel profiling mechanism result in unstable straw clearing depth, poor straw clearing quality, and the low operational efficiency of the seedbed-preparation device. In order to solve the above problems, a straw-clearing-depth self-adaptive control system of a front-mounted seedbed-preparation device was designed. The key structural design of the self-adaptive control system was completed through theoretical analysis. The performance test results of the self-adaptive control system showed that the lifting speed of the front-suspension mechanism was greater than 0.2 m/s in the manual button control mode, and the relative error between the target value and the actual value of the straw clearing depth was 10.8% under the self-adaptive profiling control mode. The three-factor and five-level quadratic regression orthogonal rotation center combination test method was adopted to conduct a parameter combination optimization test, with the machine operation speed, the operation depth of the straw clearing knife, and the straw covering amount as test factors, and the straw clearing rate, the qualified rate of operation depth, and the consistency of straw clearing between rows as evaluation indices. The results indicated that when the machine operation speed was 5~8.8 km/h, the operation depth of the straw clearing knife was 50 mm, the straw covering amount was 0.9~1.44 kg/m2, the straw clearing rate was ≥86%, the qualified rate of operation depth was ≥86%, and the consistency of straw clearing between rows was ≥83%. Field tests were carried out on the machine using operation speeds of 5 km/h, 6 km/h, 7 km/h, and 8 km/h under the conditions of an operation depth of the straw clearing knife of 50 mm and a straw covering amount of 1.2 kg/m2. The results showed that the straw clearing rate, the qualified rate of operation depth, and the consistency of straw clearing between rows were all within the optimized range under different machine operation speeds, which was basically consistent with the optimized results.