ObjectiveThe primary objective of this study is to conduct a clinical investigation involving abdominal lavage in patients with acute purulent appendicitis. The study aims to systematically assess the impact of abdominal lavage on complications within one week post-surgery and, in particular, focuses on the application value of multislice spiral CT in confirming these complications. By delving into the effects of different lavage timings on surgical outcomes and postoperative recovery, the study aims to provide scientific evidence for improving the efficacy of surgical treatment for acute purulent appendicitis.MethodsA total of 150 patients diagnosed with purulent appendicitis were selected for this study. They were divided into three groups: one group underwent preoperative abdominal lavage, another group underwent postoperative abdominal lavage , and a third group did not undergo abdominal lavage. The study aimed to compare the therapeutic outcomes among the three groups of patients. Additionally, the efficacy of the treatments was assessed by utilizing multislice spiral CT scans to confirm factors such as the abdominal abscess rate and the maximum diameter of abdominal abscesses one week postoperatively.ResultsThe operative time for patients in the experimental group showed no significant difference compared to the control group. However, postoperative pain scores were significantly lower in the experimental group (p<0.05), and the recovery time for gastrointestinal function was shortened (p<0.05) compared to the control group. The incidence of postoperative complications significantly decreased in the experimental group (p<0.05), while the control group exhibited higher complications. Additionally, the postoperative recovery status of patients in the experimental group was superior to that of the control group.ConclusionPerforming abdominal lavage in cases of purulent appendicitis can significantly alleviate postoperative pain, facilitate the recovery of gastrointestinal function, reduce the incidence of postoperative complications, and enhance overall surgical recovery. Therefore, we recommend using abdominal lavage during laparoscopic appendectomy to improve the surgical outcomes and postoperative recovery quality for patients. However, further large-scale studies are necessary to validate these results.

Objective. U-Net technology is implemented for image segmentation to diagnose cases of intestinal obstruction. To evaluate the application value of somatostatin combined with transanal intestinal obstruction decompression catheter in the treatment of distal colonic malignant intestinal obstruction and to explore the therapeutic effect of somatostatin on acute abdomen surgery in patients with intestinal obstruction. Methods. After the segmentation technique, a retrospective analysis of 30 patients with acute and complete distal colonic malignant obstruction treated by surgery was divided into a control group and an observation group according to a random number table. The treatment efficiency, clinical symptoms, disappearance time after treatment, and the incidence of complications were compared between the two groups of patients. Results. The image segmentation using U-Net can effectively assist in the medical diagnosis of the colon. Our study found that patients with combined treatment with somatostatin and anal intestinal obstruction catheter were relieved of preoperative abdominal pain and abdominal distension; compared with the abdominal circumference at the time of admission, the abdominal circumference was significantly reduced. Abdominal examination was performed 3 days after comprehensive treatment, and combined with computed tomography (CT), we observed that the measured maximum transverse diameter of the proximal colon was significantly smaller than that before treatment. Before treatment, all patients were divided into a control group and a treatment group. After treatment, the symptoms of the two groups of patients were alleviated. The treatment effective rate of the observation group was 93.3%, and the treatment effective rate of the control group was 73.3%. The effective rate was significantly higher than that of the control group, and the difference was statistically significant. Conclusions. Through the use of image segmentation technology, somatostatin treatment of early inflammatory bowel obstruction after acute abdomen surgery can effectively improve the treatment efficiency of patients, shorten the disappearance of clinical symptoms, reduce the incidence of complications, and have a significant therapeutic effect, which is worthy of clinical application. Somatostatin combined with enteral obstruction catheter treatment is safe and effective for elderly patients with acute distal large bowel malignant intestinal obstruction. It has a higher completion rate of laparoscopic surgery and a first-stage anastomosis power, which reduces the risk of perioperative period and reduces the patient's financial burden.

Automotive air conditioning (AAC) system with a variable displacement compressor (VDC) sometimes tends to experience hunting problems, where the system undergoes oscillation. The purpose of this paper is to study the hunting phenomena in this system and to find out the factors to cause the system stability by experimental investigation. In this paper, the test bench and testing method are described and four kinds of hunting phenomena summarized from our experiments are introduced in detail, i.e., hunting of the evaporator and thermal expansion valve (TEV) control loop, hunting in the AAC system with a VDC and fixed-area throttling device, hunting in the AAC system with a AAC and TEV, and hunting of ungoverned AAC system. Some analyses are made on this four hunting phenomena. These conclusions will give a further understanding for hunting phenomena of the automotive air conditioning system with a variable displacement compressor. INTRODUCTION The compressor capacity in an automotive air conditioning system with a constant displacement compressor is controlled by cycling off and on thereby creating an engine disturbance, which is becoming more noticeable as vehicles and engines become smaller. The infinitely variable displacement wobble plate compressor (here-after called “the variable displacement compressor” or VDC) was developed to address this problem. This type of compressor changes the angle of the wobble plate, and the piston stroke length, and the displacement consequently according to an increase or decrease of the pressure differential between the wobble-plate case and the suction chamber of the cylinder head to exactly match the vehicle air conditioning demand. The system has the advantages such as smooth continuous compressor operation, more comfortable environment inside the car, no frost formation in the evaporator and improved fuel economy compared to a system that cycles the compressor off and on to control capacity (Skinner, T.J 1985 and Takai, K 1989). However in the automotive air conditioning system with a variable displacement compressor, there is the hunting phenomenon sometimes, i.e., all parameters such as the refrigerant mass flow rate, refrigerant pressures and temperatures at different points, and the supply air temperature oscillate with constant amplitude and constant period. The instability can lead lower safety, lower life span and higher energy consumption and restrains its broad application. Inoue, A. et al (1988) had made an experimental investigation on evaluation of VDC with TEV in an AAC system, the interrelationship of refrigerant flow rate adjustment of VDC and TEV and the influence of VDC and TEV on system hunting were analyzed. Tian, C.Q et al (2000, 2001) had analyzed the factors that influence system stability by the experimental investigation into an AAC system with a VDC and TEV. But above researches just dealt with the AAC system with a VDC and TEV and many problems remain unresolved. The paper tries to study the hunting phenomena in the AAC system with a VDC this system and to find out the causes to raise the system stability by experimental investigation. TEST SYSTEM The test bench, shown in Figure 1, was built inside two environmental chambers. The compressor, the condenser and the receiver were placed in the outdoor environmental chamber, the evaporator and the throttling device in indoor one. Both chambers can keep constant temperature and humidity needed in our experiments. The whole system includes main experimental body, the control system and the measure system. The main body in the test system contains the compressor, the condenser, the receiver, the evaporator and the throttling device. The compressor used here is a 5 cylinder; wobble plate type, infinitely variable displacement compressor, whose displacement range is from 10 to 156 cc (cubic centimeter per revolution). The condenser is parallel type, the evaporator core is tube-fin type, the evaporator fan is driven by a four-speed motor. There are two throttling devices installed in parallel in this test system, the one throttling device is the thermal expansion valve and the other is the electronic expansion valve (pulse motor controlled) that is manually controlled and can be regarded as a fixed area throttling device when not be adjusted. So the test system can be used to observe the hunting phenomena of the AAC systems with a VDC and TEV or with a VDC and fixed area throttling device like orifice tube.

The performance of control valve is analyzed in this paper in order to study characteristics of the variable displacement wobble plate compressor. The forces acting on the control valve are analyzed and the mathematical model to analyze its performance is developed. A test bench is set up to get the steady and dynamic performance of control valve. The steady-state performances predicted by the mathematical model agree well with the experimental data while the predicted dynamic performances agree with the experimental results qualitatively. With the mathematical model, the steady-state performances of the control valve with four different preset control points and three different effective areas of the evacuated bellows have been analyzed, and the dynamic behavior of one type control valve has been studied. It is shown that: (1) the suction pressure at preset control point is inversely proportional to the discharge pressure; (2) the larger the starting force of spring in control valve or the smaller the effective area of evacuated bellows, the larger the suction pressure at preset control point; and the larger the starting force of spring in control valve and the smaller the maximum opening of ball valve, the more quickly the crankcase pressure changes and the smaller mass flow rate of control valve; the slope ratio of crankcase pressure to suction pressure cannot be influenced by the starting force of spring in control valve but can be influenced by the effective area of evacuated bellows; (3) the transition time of the crankcase pressure is about 1 s and can be neglected when working condition changes.

The aim of this paper is to find out the steady-state performance and piston-stroke-length control behaviour of a variable displacement wobble-plate compressor for an automotive air-conditioning system by experimental investigation. First, a new method and device to measure the piston stroke length of the variable displacement compressor has been developed, with which the test bench for the variable displacement compressor has been set up. Second, the steady-state performance of the variable displacement compressor, such as the relative volumetric efficiency and the relative isentropic efficiency at partial piston stroke length, has been obtained. The influence of the work condition and compressor rotary speed on the relative volumetric efficiency can be neglected according to the test data. Finally, the critical wobble-plate case pressure is proposed in this paper to judge whether the piston stroke length will change or not. The critical wobble-plate case pressure when the piston stroke length decreases is greater than that when the piston stroke length increases, which is less influenced by the piston stroke length itself from the test data. The higher the compressor discharge pressure or rotary speed, the greater the critical wobble-plate case pressure. The piston stroke length can be adjusted automatically along with the air-conditioning load when the compressor rotary speed or air conditioning load changes.

A test system with the variable displacement compressor (VDC) for automotive air conditioning system is built to study the changing rule of piston stroke length (PSL). It is found from our experiments that the critical suction pressure where the PSL starts to decrease is less than that where the PSL starts to increase for the same PSL; between the two critical lines, a hysteresis zone is formed, within which all the steady-state points fall and there is a multiple-valued relationship between VDC parameters; and the PSL is kept invariable when the VDC parameters change within the hysteresis zone. In order to find out the reason causing the hysteresis zone and to analyze the influence of the compressor parameters on the hysteresis zone, a steady-state mathematical model of VDC is developed and verified by our experimental data. The theoretical analysis indicates that the hysteresis zone is caused by the frictional forces among the moving components of VDC, and the greater the frictional forces, the broader the hysteresis zone and the larger the changing range of suction pressure. The influence of the discharge pressure and rotary speed on the hysteresis zone is that the hysteresis zone moves in the direction of the suction pressure decreasing along with the increase of the discharge pressure or rotary speed.

A test system is built first in order to investigate the instability of the automotive air conditioning (AAC) system with a variable displacement compressor (VDC), and hunting phenomena caused by the large external disturbance in the AAC system with a VDC and a thermal expansion valve, and in the AAC system with a VDC and a fixed-area throttling device are investigated experimentally in part 1 of this paper. The experimental results indicate that there also exist the hunting phenomena in the AAC system with a fixed-area throttling device. The system stability is found to be dependent on the direction of the external disturbance, and the system is apt to cause hunting when the condensing pressure decreases excessively since it may cause two-phase state at the throttling device inlet and make a large disturbance to the system. The piston stroke length will oscillate only when the oscillation amplitudes of forces acting on the wobble plate are great enough, otherwise the piston stroke length will be kept invariable, and then the system instability rule is also suitable for the AAC system with a fixed displacement compressor. From the experimental results, it is concluded that the two-phase flow at the throttling device inlet or at the evaporator outlet is the necessary condition but not sufficient condition for system hunting. Finally, a new concept, conservative stable region, is proposed based on the experimental results and theoretical analysis.

Fresh air age is an important index to evaluate indoor environment. The conventional method for measuring or calculating fresh air age is only suitable for simple ventilation systems and not for central ventilation systems. In this paper, an algorithm for calculating fresh air-age in central ventilation system is presented, which is based on the analysis of air flow in duct and air mixing. An example is given to illustrate the algorithm. The fresh air age in every ventilated room and duct can be acquired after all rooms and duct are directly calculated in turn without iteration. The algorithm is suitable,for different central ventilation systems.

介绍了地下水源热泵机组与地板供暖结合的供暖系统,分析了两者结合应用的优点.对该系统和城市集中供热和散热器系统、城市集中供热和地板供暖系统、电加热地板供暖系统从一次能源消耗、初投资、运行费用等各方面进行了比较.技术经济分析表明,类似延边地区这种冬季采暖期长、地下水资源较丰富的地区,采用地下水源热泵与地板供暖系统相结合有很大的优势.

介绍了变排量压缩机的调节机理以及压缩机调节性能试验装置,给出了空调负荷渐变以及不同压缩机转速情况下活塞行程、制冷剂质量流量等参数的变化规律,对活塞行程变化时需要的摇板箱和吸气压力差值与活塞行程变化方向、活塞行程大小以及压缩机转速的关系进行了分析.

Air age is an important index to evaluate indoor air quality in ventilated rooms. The traditional definition of air age is limited to the indoor part (i.e., the air age at the inlets of air supply diffusers is assumed to be zero). Total air age extends the traditional air age concept by considering the influence of air delivery process on air age distribution. In this paper, we report the development of an algorithm to calculate total air age in a room ventilated by multiple air-handling units (AHUs). Compared to the conventional iteration method, the new algorithm is much faster in obtaining a solution of total air age. The total air age distribution in a large space ventilated by 16 AHUs is calculated using the algorithm.

A method was developed to measure the piston stroke and to determine the static and dynamic characteristics of a variable displacement compressor. The piston stroke was calculated from the measured displacement of the journal pivot pin with the relation between the piston stroke and the displacement of the journal pivot pin derived from the geometrical relationships between the compressor parts. The measures, as a simple and reliable measurement method, indicate when and how the piston stroke of the variable displacement compressor changes. The test data shows that the relative volumetric efficiency is proportional to the relative piston stroke and that changes in the piston stroke can be determined by the pressure differential between the wobble plate case and the suction chamber.

详细测量了北京某体育馆比赛大厅的工作区及非工作区在非等温送风情况下的温度及速度分布,利用实测结果分析评价了该大厅的气流组织状况,为同类大空间建筑的气流组织研究和工程设计提供了参考.

根据研究对象不同,制冷系统稳定性可分为蒸发器完全蒸干点随机振荡现象研究、蒸发器和热力膨胀阀控制回路稳定性研究和定容量制冷系统稳定性研究三个阶段.对变排量压缩机汽车空调制冷系统的稳定性问题进行了初步分析,指出该系统中两个流量调节装置存在相互之间的参数耦合和调节协调问题.根据系统使用情况及其非线性的特点,可将变排量压缩机汽车空调制冷系统稳定性划分为小扰动稳定性和大扰动稳定性.

通风换气的新风年龄是评价室内空气品质的一个很重要指标, 传统的测量和计算方法不能适用于越来越普遍采用的集中通风系统. 通过分析空气在风道中的流动和多股空气混合时的新风年龄计算方法, 给出了适用于集中通风系统新风年龄的计算方法和示例. 该方法不需在各个房间之间进行迭代, 只需依次求解即可一次得到所有房间和风道中的新风年龄值 , 并能适用于常见的各种集中通风系统.

调查分析了北京地区体育馆上座情况 ,得出了非满座情况下的人员分布规律。对不同上座率下的负荷进行了比较。提出计算上座率的概念 ,用计算流体动力学 （CFD）技术对不同上座率下观众席温度分布进行预测和评价 ,得到了符合最佳技术经济条件的计算上座率。

The audiences' distribution and its application on energy consumption in gymnasium are focused on. Based on investigation results of some gymnasiums in Beijing, the attending-rate of audiences for sport game is analyzed, and the characteristic of audiences' distribution in sport hall of gymnasium is summed up. By numerical simulation, cooling loads and temperature distribution of audiences' area in different attending-rates are evaluated. Then a new concept on calculated-attending-rate(CAR) is proposed. And using CAR, a new idea in designing air-conditioning system is outlined to get the lower energy consumption and reach more efficient investment and operating fee.