Performance Simulation of a Double Tube Heat Exchanger Based on Different Nanofluids by Aspen Plus

A heat exchanger’s performance depends heavily on the operating fluid’s transfer of heat capacity and thermal conductivity.Adding nanoparticles of high thermal conductivity materials is a significant way to enhance the heat transfer fluid’s thermal conductivity.This research used engine oil containing alumina(Al_(2)O_(3))nanoparticles and copper oxide(CuO)to test whether or not the heat exchanger’s efficiency could be improved.To establish the most effective elements for heat transfer enhancement,the heat exchangers thermal performance was tested at 0.05%and 0.1%concentrations for Al_(2)O_(3)and CuO nanoparticles.The simulation results showed that the percentage increase in Nusselt number(Nu)for nanofluid at 0.05%particle concentration compared to pure oil was 9.71%for CuO nanofluids and 6.7%for Al_(2)O_(3)nanofluids.At 0.1%concentration,the enhancement percentage in Nu was approximately 23%for CuO and 18.67%for Al_(2)O_(3)nanofluids,respectively.At a concentration of 0.1%,CuO nanofluid increased the LMTD and overall heat transfer coefficient(U)by 7.24 and 5.91%respectively.Both the overall heat transfer coefficient(U)and the heat transfer coefficient(hn)for CuO nanofluid at a concentration of 0.1%increased by 5.91%and 10.68%,respectively.The effectiveness(εn)of a heat exchanger was increased by roughly 4.09%with the use of CuO nanofluid in comparison to Al_(2)O_(3)at a concentration of 0.1%.The amount of exergy destruction in DTHX goes down as Re and volume fractions go up.Moreover,at 0.05%and 0.1%nanoparticle concentrations,the percentage increase in dimensionless exergy is 10.55%and 13.08%,respectively.Finally,adding the CuO and Al_(2)O_(3)nanoparticles improved the thermal conductivity of the main fluid(oil),resulting in a considerable increase in the thermal performance and rate of heat transfer of a heat exchanger.

Effect of Empowering Education on Refined Nursing of Patients with Internal Double J Tubes after Surgery for Ureteral Stricture

Objective: To investigate the effect of the theory of enabling education on the fine management of patients with internal double J tubes after ureteral stricture. Methods: Eighty patients with built-in double J tubes after ureteral stricture were selected from the urology department of a grade a hospital in Guangzhou. The patients were divided into control group and observation group by random number method, with 40 patients in each group. The control group received refined nursing after surgery, while the observation group received refined nursing including the theory of empowerment education after surgery on the basis of the control group. Results: After the intervention, the observation group had a higher standard rate of quality indicators, higher self-efficacy score than the control group (P ≤ 0.05), lower scores of ureteral stent-related symptoms, urinary system symptoms, pain symptoms, total health status, job performance, additional problems and total scores than the control group (P ≤ 0.05), and statistically significant differences were found in the total health status dimension and total scores (P ≤ 0.01). The nursing satisfaction survey, the scores of clinical nursing, health education, psychological counseling and nurse-patient communication were all higher than those in the control group (P ≤ 0.05), and the differences in health education and nurse-patient communication were statistically significant (P ≤ 0.01). Conclusion: The theory of enabling education can improve patients’ self-nursing level, promote the implementation of refined nursing quantitative indicators and nursing measures, relieve the poor symptoms of ureteral stricture patients, and improve patients’ satisfaction with nursing work.

Double aortic arch and nasogastric tubes: A fatal combination

Double aortic arch is a common form of complete vascular ring that encircles both the trachea and the esophagus, and presents with various respiratory and esophageal symptoms, usually in the pediatric population. We present a case of double aortic arch in an adult patient that manifested as massive upper gastrointestinal bleeding after prolonged nasogastric intubation.

Design of a re-entrant double-staggered ladder circuit for V-band coupled-cavity traveling-wave tubes

The re-entrant double-staggered ladder slow-wave structure is employed in a high-power V-band coupled-cavity traveling-wave tube. This structure has a wide bandwidth, a moderate interaction impedance, and excellent thermal dissipation properties, as well as easy fabrication. A well-matched waveguide coupler is proposed for the structure. Combining the design of attenuators, a full-scale three-dimensional circuit model for the V-band coupled-cavity traveling- wave tube is constructed. The electromagnetic characteristics and the beam wave interaction of this structure are investigated. The beam current is set to be 100 mA, and the cathode voltage is tuned from 16.8 kV to 15.8 kV. The calculation results show that this tube can produce a saturated average output power over 100 W with an instantaneous bandwidth greater than 1.25 GHz in the frequency ranging from 58 GHz to 62 GHz. The corresponding gain and electronic efficiency can reach over 32 dB and 6.5%, respectively.

Double J管在体外震波碎石中的应用

本文对20例鹿角形、铸形、多发结石在ESWL之前放置Double J管,平均4周后拔管,拔管时15例结石全部排出,5例大部排出(剩下的为结石碎片)。除1例既往有泌尿道感染史术后出现高热而行肾切除外,余19例均无术后感染、肾积水等并发症发生。并对胶管选择、适应证、拔管指征等进行了讨论。

输尿管软镜钬激光碎石术治疗输尿管上段复杂性结石后双J管附壁结石形成的原因分析

目的:分析输尿管软镜钬激光碎石术治疗输尿管上段复杂性结石后双J管附壁结石形成的原因。方法:选择2015年1月至2023年8月于首都医科大学附属北京潞河医院收治的105例输尿管上段复杂性结石患者,其中男58例,女47例,根据结石评估结果分为结石组(n=40)与非结石组(n=65)。通过随机森林算法分析患者双J管附壁结石形成的影响因素。通过单因素和多因素分析双J管附壁结石形成的独立影响因素,并构建分类树模型。结果:结石组和非结石组CT值、术中出血量、双J管留置时间、白细胞计数(WBC)、C反应蛋白(CRP)、尿酸(UA)、血钙、尿pH值、尿蛋白、尿红细胞、尿白细胞、尿结晶比较差异均有统计学意义(t/χ^(2)值分别为4.361、2.502、6.815、12.176、24.398、15.595、6.517、2.069、6.881、4.524、3.883、4.699,均P<0.05)。双J管留置时间、尿蛋白阳性、尿结晶阳性、UA为双J管附壁结石形成的独立危险因素(P<0.05)。分类树模型显示,双J管留置时间是双J管附壁结石形成的重要预测因素,收益图和索引图显示模型预测良好。结论:双J管留置时间、尿蛋白阳性、尿结晶阳性、UA为双J管附壁结石形成的独立危险因素。临床应重点关注相关因素,及时制定预防策略,以期降低双J管附壁结石的发生风险。

耳穴揿针联合坦索罗辛对输尿管镜碎石术后留置双J管患者USSQ评分及满意度的影响

目的:观察耳穴揿针联合坦索罗辛对输尿管镜碎石术后留置双J管患者输尿管支架相关症状调查问卷(USSQ)评分及满意度的影响。方法:选取74例输尿管镜碎石术后留置双J管患者为观察对象,按随机数字表法分为观察组及对照组各37例。观察组给予常规护理、口服坦索罗联合耳穴揿针治疗,对照组给予常规护理、口服坦索罗联合耳穴压豆治疗。疗程均为6 d,比较2组治疗后USSQ评分及治疗满意度。结果:治疗前,2组USSQ评分比较,差异无统计学意义(P>0.05)。治疗6 d后,2组USSQ评分均较治疗前及治疗3 d下降(P<0.05),并呈明显下降趋势(P<0.05);且观察组相同时间点USSQ评分均低于对照组(P<0.05)。治疗结束后,观察组满意度为97.30%,对照组为83.78%,2组比较,差异有统计学意义(P<0.05)。结论:耳穴揿针联合坦索罗辛可有效改善输尿管镜碎石术后留置双J管患者相关症状和生活质量,提高其治疗满意度。

基于授权理论的护理对泌尿结石术后留置双J管患者自我管理能力和并发症的影响

目的:探讨基于授权理论的护理对泌尿结石术后留置双J管患者自我管理能力和并发症的影响。方法:选取2021年1月—2022年12月宜昌市中心人民医院收治的200例泌尿结石术后留置双J管患者。随机将其分为对照组与试验组,各100例。对照组给予常规护理,试验组在对照组基础上给予基于授权理论指导的护理。比较两组护理前后自我管理能力,并发症。结果:护理后,两组自我管理行为、自我管理认知、自我管理环境评分及总分均升高,试验组自我管理行为、自我管理认知、自我管理环境评分及总分均高于对照组,差异有统计学意义(P<0.05)。试验组尿路感染、血尿、膀胱刺激征并发症发生率均显著低于对照组,差异有统计学意义(P<0.05)。结论:对泌尿结石术后留置双J管患者实施基于授权理论的护理,能够提升患者自我管理能力,有助于减少并发症的发生。

Ureteral double J stent displaced into vena cava and management with laparoscopy: A case report and review of the literature

We reported displacement of a ureteral double J stent into the vena cava and laparoscopic management in a 69-year-old patient with a history of ureteral stent placement. Preoperative computed tomography and plain X-rays showed malpositioning of the double J stent and displacement into the inferior vena cava. The characteristics of stent misplacement precluded endovascular procedures and explorative laparoscopic surgery was performed. The intra-and postoperative periods were uneventful. Postoperative imaging demonstrated that the new double J stent was in the right position. The patient was discharged 7 d after the operation and was symptom free at the 4-mo followup.

Effect of cyclotron resonance on ‘hot’ dispersion in a staggered double metallic grating sheet beam travelling wave tube

Based on the beam wave synchronous interaction in transverse and longitudinal directions at the same time and starting from Maxwell’s equation and linear Vlasov equation, the beam–wave interaction ‘hot’ dispersion equation considering both cyclotron resonance and Cherenkov resonance in a staggered double metallic grating traveling wave tube is deduced.Through the reasonable selection for geometric and electrical parameters, the numerical calculation and analysis of the ‘hot’ dispersion equation shows that the beam–wave interaction gain and frequency band with the cyclotron resonance enhancement effect are higher than those with only Cherenkov resonance radiation.

A staggered double vane circuit for a W-band traveling-wave tube amplifier

Based on the combination of a staggered double vane slow wave structure （SWS） and round electron beam, a 200-W W-band traveling-wave tube （TWT） amplifier is studied in this paper. The main advantages of round beam operation over the sheet beam is that the round beam can be formed more easily and the focus requirement can be dramatically reduced. It operates in the fundamental mode at the first spatial harmonic. The geometric parameters are optimized and a transition structure for the slow wave circuit is designed which can well match the signal that enters into and goes out from the tube. Then a TWT model is established and the particle-in-cell （PIC） simulation results show that the tube can provide over 200-W output power in a frequency range of 88 GHz-103 GHz with a maximum power of 289 W at 95 GHz, on the assumption that the input power is 0.1 W and the beam power is 5.155 kW. The corresponding conversion efficiency and gain at 95 GHz are expected to be 5.6% and 34.6 dB, respectively. Such amplifiers can potentially be used in high power microwave-power-modules （MPM） and for other portable applications.

Remote Control System of 37 mm Double Tube Antiaircraft Gun for Hunan Weather Modification

Hunan Weather Modification Center and Suizhou Dafang Precision Electromechanical Engineering Co.,Ltd. of Hubei commonly transformed and installed 83 double tube antiaircraft guns( 37 mm) of Hunan Province in order to realize remote control of computer. After transformation,loading capacity of ammunition feeding machine became large,which could shorten the time of filling shells in the case of short airspace time;one shell launch volume was more,which could improve hail suppression effect; the degree of automation was greatly improved,which could save manpower by more than 50%. It fully embodied the modernization level of Hunan weather modification operation.

艾灸联合索利那新对输尿管软镜碎石术后双J管相关并发症的影响

目的:探讨艾灸与索利那新联合应用治疗输尿管软境碎石术后双J管相关并发症及附管结石的临床效果。方法:将100例输尿管软境碎石术后置入双J管的上尿路结石患者随机分为对照组(50例)和观察组(50例)。两组患者均给予常规护理及抗感染、镇痛等对症治疗。对照组患者术后第1天开始给予索利那新口服治疗,观察组在此基础上加以对关元和气海进行艾灸。记录并评估治疗前、第1个疗程结束后、第2个疗程结束后3个时间节点两组患者USSQ评分表中6个部分的评分变化,输尿管软境碎石术术后4周,对拔除双J管后的结石清除率、附管结石的总有效率、尿路感染和血尿情况进行比较。结果:第2个疗程结束后,与治疗前比较,两组患者排尿症状、疼痛、整体健康情况、工作表现评分均降低(P<0.05)。第1、2个疗程结束后,与对照组比较,观察组患者排尿症状、疼痛、整体健康情况评分、工作表现均降低(P<0.05)。观察组患者结石清除率、附管结石的总有效率高于对照组(P<0.05)。结论:艾灸联合索利那新治疗输尿管软境碎石术后双J管相关症状及双J管附管结石形成疗效显著,安全性好,无不良反应。

延续性护理在泌尿外科手术放置双J管患者中的应用研究

目的分析延续性护理对于泌尿外科手术放置双J管患者的临床应用价值。方法回顾性选取2022年11月—2023年11月宁夏回族自治区固原市人民医院泌尿外科收治的100例尿路梗阻并携带双J管患者的临床资料,根据不同护理方式分为观察组(n=50)和对照组(n=50),两组患者院内均进行常规护理,观察组增加出院后延续性护理。比较两组患者依从性、带管期间并发症发生率、护理满意度、生活质量评分。结果观察组依从性为94.00%(47/50),高于对照组的80.00%(40/50),差异有统计学意义(χ^(2)=4.333,P<0.05)。观察组护理满意率为98.00%(49/50),高于对照组的84.00%(42/50),差异有统计学意义(χ^(2)=4.396,P<0.05)。观察组带管期间并发症发生率为4.00%(2/50),低于对照组的20.00%(10/50),差异有统计学意义(χ^(2)=6.061,P<0.05)。护理后,观察组生活质量评分高于对照组,差异有统计学意义(P<0.05)。结论延续性护理通过对患者的持续观察和监测,能够及时发现并处理患者出现的问题,从而降低并发症的发生率,提高患者依从性、护理满意度和生活质量。

基于健康行动过程取向模型的护理干预在泌尿系结石术后留置双“J”管患者中的应用

目的:探讨基于健康行动过程取向(health action process approach,HAPA)模型的护理干预在泌尿系结石术后留置双“J”管患者的应用效果。方法:选取2023年10月至2024年1月符合纳入、排除标准的泌尿系结石术后留置双“J”管患者70例,根据病房号分为两组,分别为HAPA模型护理干预组和常规护理组,每组均有35例参与者。常规护理组接受泌尿外科的常规围手术期护理措施,在HAPA模型护理干预组中,除了进行常规护理组护理措施外,还采用基于HAPA模型的护理干预。对比两组患者在术后第3日、出院时、出院后第7天的腰痛评分、返院拔管时的并发症发生率、健康知识知晓率以及护理满意度。结果:两组患者一般资料差异均无统计学意义(均P>0.05),健康行动过程模型组患者在术后第3天、出院时、出院后第7天的腰痛评分与常规组相比,显著降低;健康行动过程模型组患者健康知识知晓率、护理满意度与常规组相比,显著提高,差异均有统计学意义(均P<0.05),两组患者的并发症发生率差异无统计学意义(P>0.05)。结论:基于HAPA模型的护理干预能有效减少泌尿系结石术后留置双“J”管患者的疼痛程度,提高患者健康知识知晓率和护理满意度。

Experimental study on the seismic behavior of high strength concrete fi lled double-tube columns

To study the seismic behavior of high strength concrete fi lled double-tube(CFDT) columns,each consisting of an external square steel tube and an internal circular steel tube,quasi-static tests on eight CFDT column specimens were conducted.The test variables included the width-to-thickness ratio(β1) and the area ratio(β2) of the square steel tube,the wall thickness of the circular steel tube,and the axial force(or the axial force ratio) applied to the CFDT columns.The test results indicate that for CFDT columns with a square steel tube with β1 of 50.1 and 24.5,local buckling of the specimen was found at a drift ratio of 1/150 and 1/50,respectively.The lateral force-displacement hysteretic loops of all specimens were plump and stable.Reducing the width-to-thickness ratio of the square steel tube,increasing its area ratio,or increasing the wall thickness of the internal circular steel tube,led to an increased fl exural strength and deformation capacity of the specimens.Increasing the design value of the axial force ratio from 0.8 to 1.0 may increase the fl exural strength of the specimens,while it may also decrease the ultimate deformation capacity of the specimen with β1 of 50.1.

上尿路结石术后并发双J管相关性尿路感染列线图风险预测模型的构建

目的:探讨上尿路结石病人术后并发双J管相关性尿路感染的危险因素,并构建其列线图风险预测模型。方法:回顾性收集2020年7月-2022年6月某三级甲等综合医院收治的216例上尿路结石并留置双J管病人,根据双J管相关性尿路感染的发病情况将其分为感染组与非感染组,采用单因素分析、Logistic回归分析上尿路结石病人术后并发双J管相关性尿路感染的危险因素,构建列线图风险预测模型并评价该模型的实际效用。结果:上尿路结石病人术后并发双J管相关性尿路感染29例(13.43%)。Logistic回归分析结果显示,合并糖尿病、中性粒细胞与淋巴细胞比值(NLR)和肾积水程度是上尿路结石病人术后并发双J管相关性尿路感染的独立危险因素。列线图风险预测模型内部验证结果显示,Hosmer-Lemeshow检验χ^(2)=6.981,P=0.639,ROC曲线下面积为0.853[95%CI(0.774,0.934)]。结论:构建的列线图风险预测模型具有良好的预警作用,为医护人员早期识别上尿路结石术后并发双J管相关性尿路感染的高危人群,及时采取有效的预防措施降低感染率提供依据。

Asymptotic solutions of the flow of a Johnson-Segalman fluid through a slowly varying pipe using double perturbation strategy

A double perturbation strategy is presented to solve the asymptotic solutions of a Johnson-Segalman （J-S） fluid through a slowly varying pipe. First, a small parameter of the slowly varying angle is taken as the small perturbation parameter, and then the second-order asymptotic solution of the flow of a Newtonian fluid through a slowly varying pipe is obtained in the first perturbation strategy. Second, the viscoelastic parameter is selected as the small perturbation parameter in the second perturbation strategy to solve the asymptotic solution of the flow of a J-S fluid through a slowly varying pipe. Finally, the parameter effects, including the axial distance, the slowly varying angle, and the Reynolds number, on the velocity distributions are analyzed. The results show that the increases in both the axial distance and the slowly varying angle make the axial velocity slow down. However, the radial velocity increases with the slowly varying angle, and decreases with the axial distance. There are two special positions in the distribution curves of the axial velocity and the radial velocity with different Reynolds numbers, and there are different trends on both sides of the special positions. The double perturbation strategy is applicable to such problems with the flow of a non-Newtonian fluid through a slowly varying pipe.

Techno-economic analysis of single U-tube and double U-tube heat exchangers in Chongqing area

On the basis of practical projects in Chongqing,the thermal performance of heat exchangers (single U-tube type and double U-tube type) of the ground-source heat pump (GSHP) system in the hot summer was obtained and analyzed. The data obtained from test could match with the result deduced from theoretical calculation. From the test results,the cooling capacity of double U-tube is 1.6 times that of single U-tube. Taking cost per depth per watt Clq as the evaluation standard,Clq of single U-tube is 4.69 RMB$/W,and Clq of double U-tube is 3.14 RMB$/W. The double U-tube heat exchangers usage should be prioritized.