Experimental Study of Air Conditioning Unit of Evaporative Cooling Assisted Mechanical Refrigeration

The evaporative cooling,which assists the refrigeration machinery air-conditioning systems test-rig,has been designed.Its structure and working principle were described,and the performance test was conducted and analyzed.The test shows that making full use of the evaporative cooling "free cooling" in Spring and Autumn seasons can fully meet the requirements of air-conditioned comfort through the switch of the function in different seasons.Taking into account the evaporative cooling fan and pump energy consumption,compared with the traditional mechanical refrigeration system,more than 80 percent of energy can be saved,and the energy efficiency ratio of the Unit(EER)is as high as 7.63.Using the two stages of indirect evaporative cooling to pre-cool the new wind in summer,under the conditions of the same air supply temperature requirements,0.83 kg/s chilled water saved can be equivalent to the traditional mechanical refrigeration system,and when the new wind ratio up to 50 percent,more than 10 percent load was reduced in mechanical refrigeration system.The overall EER increased about 35 percent.

Improvement of Mechanical Stability for Single Unit Recording Based on Skull Cap in Living Chinchilla

Three-point head fixation was constructed to provide mechanical stability for single unit recording(SUR)on vestibular sensory system in living chinchilla previously.However,it is no more qualified to this work when the stimulation intensity becomes large because of frequent unit losing and neuron damage,which strongly implies that the mechanical stability has been broken during the stimulation.Here,we constructed a novel hea0 fixation(skull cap assistant head fixation)provided by skull cap on the basis of three-point head fixation in order to improve the mechanical stability for SUR under the stimulation with large magnitude.The large area bone connection is the feature and advantage of this improved method,which directly fixes the tested local nervous tissue and microelectrode in an intact stable system through skull cap except two ear bars and a tube face mask.Our data exhibited that skull cap assistant head fixation could significantly improve the success rate of neural response activity recording in the population of semicircular canal neurons under the stimulation with large intensity(amplitudd 00 deg/s).Based on the analysis of neural response activity and noise base-line during stimulation,our data further indicated that this method could significantly improve the mechanical stability for SUR during high-speed motion stimulation on vestibular system in living chinchilla.Skull cap assistant head fixation extends the application of SUR on vestibular neuron in linear response range and provides a solid foundation for electrophysiological research on vestibular sensory system in fhrther studies.

Evaluation of progressive early rehabilitation training mode in intensive care unit patients with mechanical ventilation

BACKGROUND Mechanical ventilation is a common resuscitation method in the intensive care unit(ICU).Unfortunately,this treatment process prolongs the ICU stay of patients with an increased incidence of delirium,which ultimately affects the prognosis.AIM To evaluate the effect of progressive early rehabilitation training on treatment and prognosis of patients with mechanical ventilation in ICU.METHODS The convenience sampling method selected 190 patients with mechanical ventilation admitted to the Fourth Hospital of Hebei Medical University from March 2020 to March 2021.According to the random number table method,they were divided into the control and intervention groups.The control group received routine nursing and rehabilitation measures,whereas the intervention group received progressive early rehabilitation training.In addition,the incidence and duration of delirium were compared for the two groups along with mechanical ventilation time,ICU hospitalization time,functional independence measure(FIM)score,Barthel index,and the incidence of complications(deep venous thrombosis,pressure sores,and acquired muscle weakness).RESULTS In the intervention group,the incidence of delirium was significantly lower than in the control group(28%vs 52%,P<0.001).In the intervention group,the duration of delirium,mechanical ventilation time,and ICU stay were shorter than in the control group(P<0.001).The FIM and Barthel index scores were significantly higher in the intervention group than the control group(P<0.001).The total incidence of complications in the intervention group was 3.15%,which was lower than 17.89%in the control group(P<0.001).CONCLUSION Progressive early rehabilitation training reduced the incidence of delirium and complications in ICU patients with mechanical ventilation,which improved prognosis and quality of life.

Early mobilization for mechanically ventilated patients in the intensive care unit:a systematic review and meta-analysis

Background: Early mobilization(EM) is a regimen that was carried out by physiotherapists in a relatively early stage. It has been investigated by an increasing number of researchers. However, there has not been a meta-analysis concerning whether EM could benefit the clinical outcomes of critically ill patients requiring mechanical ventilation(MV). The present systematic review aims to evaluate the effect of EM compared with immobilization for mechanically ventilated patients.Methods: A computerized literature search was performed in six databases for related articles from inception to June 2017. We included randomized controlled trials and controlled clinical trials and used the Physiotherapy Evidence Database scale to assess the quality of included studies. Primary outcomes were measures of muscle function, duration of MV, and incidence of mortality.Secondary outcomes were adverse effects and length of stay(LOS) in intensive care unit(ICU) and hospital.Results: Eight trials were included; of those, only one study without standard EM reported that the intervention was invalid to improve the outcomes. The result of meta-analysis indicated that EM shortened the duration of MV; however, it had no positive effect on mortality and LOS in ICU.Conclusions: This review suggests that EM improves the muscle function and ventilation duration. Further research highlighting standard intervention and specific groups is needed.

Mechanical and Acoustic Performance Test of New Designed Metal Noise Barrier Unit Plate with No Riveted Connection

The modern transportation system is increasingly developed during recent years.It is an effective solution to set the noise barriers to reduce the traffic noise pollution caused by different kinds of transportation systems.Many deficiencies on concrete noise barriers and metal noise barriers with rivet structure can be eliminated by a new kind of noise barrier with no-riveted structure.The mechanical performance examination and acoustic performance test are conducted on the new-designed noise barrier with no-riveted structure.The results indicate that the maximum stress is 1.74 MPa and the maximum deformation is 1.04 mm with load acting on the unit plate.The noise reduction coefficient of this kind of no-riveted noise barrier unit plate is 0.75 and its noise insulation is 40 dB,which were conform to or superior to the standard requirements.Therefore,this new designed noise barrier meets the field application requirements of mechanical and acoustic performance,which demonstrates the noise barriers can be widely promoted.

Improved Units of Measure in Rotational Mechanics

The SI system of units in rotational mechanics yields correct numerical results, but it produces physically incorrect units of measure in many cases. SI units also violate the principle of general covariance—the general rule for defining continuous coordinates and units in mathematics and mathematical physics. After 30+ years of wrestling with these problems, the ultimate authority on units of measure has declared that Newton–meter and Joule are not equivalent in rotational mechanics, as they are in the rest of physics. This article proposes a simple modification to SI units called “Nonstandard International units” (“NI units”) until a better name is agreed upon. NI units yield correct numerical results and physically correct units of measure, and they satisfy the principle of general covariance. The main obstacle to the adoption of NI units is the consensus among users that the radius of rotation should have the unit meter because the radius can be measured with a ruler. NI units assigned to radius should have units meter/radian because the radius is a conversion factor between angular size and circumferential length, as in arclength = rθ. To manage the social consensus behind SI units, the author recommends retaining SI units as they are, and informing users who want correct units that NI units solve the technical problems of SI units.

Determinants of mechanical restraint in an acute psychiatric care unit

BACKGROUND Despite numerous attempts to reduce the use of mechanical restraint(MR),this technique continues to be widely applied in many acute psychiatric care settings.In order to reduce MR,a better understanding of the variables associated with its use and duration in different clinical environments is essential.AIM To determine the proportion of patients subjected to MR and the duration thereof in two acute care psychiatric units;and to identify the variables associated with the use and duration of MR.METHODS Descriptive study of all patients admitted to the acute psychiatric units at the Parc de Salut Mar(Barcelona,Spain)in the year 2018.The number and percentage of patients subjected to MR,as well as the duration of each episode were assessed.The following data were also registered:sociodemographic characteristics,psychiatric diagnosis,and presence of cultural and/or language barriers.Multivariate analyses were performed to assess determinants of MR and its duration.RESULTS Of the 464 patients,119(25.6%)required MR,with a median of 16.4 h per MR.Two factors-a diagnosis of psychotic disorder[Odds ratios(OR)=0.22;95%CI:0.06-0.62;P=0.005]and the presence of a language barrier(OR=2.13;95%CI:1.2-3.7;P=0.007)-were associated with a significantly higher risk of MR.Male sex was associated with a longer duration of MR(B=-19.03;95%CI:-38.06-0.008;P=0.05).CONCLUSION The presence of a language barrier and a psychotic disorder diagnosis are associated with a significantly higher risk of MR.Furthermore,male sex is associated with a longer duration of MR.Individualized restraint protocols that include the required tools are necessary to ultimately limit the use of mechanical restraint.

Overseas Interests Maintenance Mechanism and Its Enlightenment to China--To the System as the Research Object of the United States

By American post-war gradually build up national security strategy, which is based on law and mechanism, a foreign diverse practices, with international mechanism as the platform, with military force as the backing, supplemented by non-governmental forces overseas interests maintenance mechanism, the strategy and policy support, the guarantee of the military and security for the development of overseas interests to provide comprehensive protection. For our country, the United States to maintain the interests of the overseas which has important reference significance to the practice and experience, China should build overseas interests maintenance strategic framework, perfect the relevant legal system and government agencies, to enhance the use of international mechanism, reform and construction, strengthen the delivery and use of military force overseas, pay attention to the cultivation of non-governmental forces and support, to strengthen the construction of national image.

Human Rights NGOs and the United Nations Human Rights Council——Participation by the China Society for Human Rights Studies in the Universal Periodic Review Mechanism

Since its founding in 1993, the China Society for Human Rights Studies （CSHRS） has extensively participated inthe human rights work of the United Nations （UN） and has actively carried out international exchange and cooperation. In May 2012, the UN Human Rights Council （UNHRC） initiated the second round of country reviews on human rights.

Global Dynamic Modeling of Electro-Hydraulic 3-UPS/S Parallel Stabilized Platform by Bond Graph

Dynamic modeling of a parallel manipulator（PM） is an important issue. A complete PM system is actually composed of multiple physical domains. As PMs are widely used in various fields, the importance of modeling the global dynamic model of the PM system becomes increasingly prominent. Currently there lacks further research in global dynamic modeling. A unified modeling approach for the multi-energy domains PM system is proposed based on bond graph and a global dynamic model of the 3-UPS/S parallel stabilized platform involving mechanical and electrical-hydraulic elements is built. Firstly, the screw bond graph theory is improved based on the screw theory, the modular joint model is modeled and the normalized dynamic model of the mechanism is established. Secondly, combined with the electro-hydraulic servo system model built by traditional bond graph, the global dynamic model of the system is obtained, and then the motion, force and power of any element can be obtained directly. Lastly, the experiments and simulations of the driving forces, pressure and flow are performed, and the results show that, the theoretical calculation results of the driving forces are in accord with the experimental ones, and the pressure and flow of the first limb and the third limb are symmetry with each other. The results are reasonable and verify the correctness and effectiveness of the model and the method. The proposed dynamic modeling method provides a reference for modeling of other multi-energy domains system which contains complex PM.

Effects of early rehabilitation therapy on patients with mechanical ventilation

BACKGROUND: For patients in intensive care unit(ICU), mechanical ventilation is an effective treatment to survive from acute illness and improve survival rates. However, long periods of bed rest and restricted physical activity can result in side effects. This study aimed to investigate the feasibility of early rehabilitation therapy in patients with mechanical ventilation.METHODS: A randomized controlled trial was carried out. Sixty patients, with tracheal intubation or tracheostomy more than 48 hours and less than 72 hours, were admitted to the ICU of the Affiliated Hospital of Medical College, Qingdao University, from May 2010 to May 2012. These patients were randomly divided into a rehabilitation group and a control group. In the rehabilitation group, rehabilitation therapy was performed twice daily, and the training time and intensity were adjusted according to the condition of the patients. Early rehabilitation therapy included heading up actively, transferring from the supine position to sitting position, sitting at the edge of the bed, sitting in chair, transferring from sitting to standing, and ambulating bedside. The patient's body mass index, days to first out of bed, duration of mechanical ventilation, length of ICU stay, APACHE II score, highest FiO2, lowest PaO2/FiO2 and hospital mortality of patients were all compared between the rehabilitation group and the control group. The differences between the two groups were compared using Student's t test.RESULTS: There was no significant difference in body mass index, APACHE II score, highest FiO2, lowest PaO2/FiO2 and hospital mortality between the rehabilitation group and the control group(P>0.05). Patients in the rehabilitation group had shorter days to first out of bed(3.8±1.2 d vs. 7.3±2.8 d; P=0.00), duration of mechanical ventilation(5.6±2.1 d vs. 12.7±4.1 d; P=0.005) and length of ICU stay(12.7±4.1 d vs. 15.2±4.5 d; P=0.01) compared with the control group.CONCLUSION: Early rehabilitation therapy was feasible and effective in improving the outcomes of patients with mechanical ventilation.

The design, manufacture and application of multistable mechanical metamaterials-a state-of-the-art review

Multistable mechanical metamaterials are a type of mechanical metamaterials with special features,such as reusability,energy storage and absorption capabilities,rapid deformation,and amplified output forces.These metamaterials are usually realized by series and/or parallel of bistable units.They can exhibit multiple stable configurations under external loads and can be switched reversely among each other,thereby realizing the reusability of mechanical metamaterials and offering broad engineering applications.This paper reviews the latest research progress in the design strategy,manufacture and application of multistable mechanical metamaterials.We divide bistable structures into three categories based on their basic element types and provide the criterion of their bistability.Various manufacturing techniques to fabricate these multistable mechanical metamaterials are introduced,including mold casting,cutting,folding and three-dimensional/4D printing.Furthermore,the prospects of multistable mechanical metamaterials for applications in soft driving,mechanical computing,energy absorption and wave controlling are discussed.Finally,this paper highlights possible challenges and opportunities for future investigations.The review aims to provide insights into the research and development of multistable mechanical metamaterials.

Intensivists’response to hyperoxemia in mechanical ventilation patients:The status quo and related factors

BACKGROUND:Due to the still sparse literature in China,the investigation of hyperoxemia management is required.Thus,we aim to conduct a retrospective study to provide more information about hyperoxemia management in intensive care unit(ICU)patients.METHODS:We retrospectively screened the medical records of adult patients(age≥18 years)who required mechanical ventilation(MV)≥24 hours from January 1,2018,to December 31,2018.All arterial blood gas(ABG)tested during MV was retrieved,and MV settings were recorded.The median arterial partial pressure of oxygen(PaO2)>120 mmHg(1 mmHg=0.133 kPa)was defined as mild to moderate hyperoxemia,and PaO2>300 mmHg as extreme hyperoxemia.Intensivists’response to hyperoxemia was assessed based on the reduction of fraction of inspired oxygen(FiO2)within one hour after hyperoxemia was recorded.Multivariable logistic regression analysis was performed to determine the independent factors associated with the intensivists’response to hyperoxemia.RESULTS:A total of 592 patients were fi nally analyzed.The median Acute Physiology and Chronic Health Evaluation II(APACHE II)score was 21(15-26).The PaO2,arterial oxygen saturation(SaO2),FiO2,and positive end expiratory pressure(PEEP)were 96.4(74.0-126.0)mmHg,97.8%(95.2%-99.1%),0.4(0.4-0.5),and 5(3-6)cmH2O,respectively.Totally 174(29.39%)patients had PaO2>120 mmHg,and 19(3.21%)patients had extreme hyperoxemia at PaO2>300 mmHg.In cases of mild to moderate hyperoxemia with FiO2≤0.4,only 13(2.20%)patients had a decrease in FiO2 within one hour.The multivariable logistic regression analysis showed that a positive response was independently associated with FiO2(odds ratio[OR]1.09,95%confi dence interval[CI]1.06-1.12,P<0.001),PaO2(OR 1.01,95%CI 1.00-1.01,P=0.002),and working shifts(OR 5.09,95%CI 1.87-13.80,P=0.001).CONCLUSIONS:Hyperoxemia occurs frequently and is neglected in most cases,particularly when mild to moderate hyperoxemia,hyperoxemia with lower FiO2,hyperoxemia during night and middle-night shifts,or FiO2 less likely to be decreased.Patients may be at a risk of oxygen toxicity because of the liberal oxygen strategy.Therefore,further research is needed to improve oxygen management for patients with MV in the ICUs.

ELECTRO-HYDRAULIC SERVO SYSTEM IN THE CENTRIFUGE FIELD

The mechanical characteristics of the electro-hydraulic servo system in thecentrifuge field are analyzed. The hydraulic pressure law in the centrifuge field indicates theexistence of the centrifuge hydraulic pressure. The mechanical characteristics of the slide-valveand the dual nozzle flapper valve are studied, and it is found that the centrifuge field can notonly increase the driving force or moment of the function units, but also decrease the stability ofthe components. Finally by applying Gauss minimum constraint principle, the dynamic model of theelectro-hydraulic vibrator in the centrifuge field is established, and the mechanical restriction ofthe system is also presented. The study will be helpful for the realization of the combinedvibration and centrifuge test system.

A Comparison of Shale Gas Fracturing Based on Deep and Shallow Shale Reservoirs in the United States and China

China began to build its national shale gas demonstration area in 2012.The central exploration,drilling,and development technologies for medium and shallow marine shale reservoirs with less than 3,500m of buried depth in Changning-Weiyuan,Zhaotong,and other regions had matured.In this study,we macroscopically investigated the development history of shale gas in the United States and China and compared the physical and mechanical conditions of deep and shallow reservoirs.The comparative results revealed that themain reasons for the order-ofmagnitude difference between China’s annual shale gas output and the United States could be attributed to three aspects:reservoir buried depth,reservoir physical and mechanical properties,and engineering technology level.The current engineering technology level of China could not meet the requirements of increasing production and reducing costs for deep shale gas reservoirs;they had reached the beneficial threshold development stage and lacked the capacity for large-scale commercial production.We identified several physical and mechanical reasons for this threshold development stage.Deep shale reservoirs were affected by the bedding fracture,low brittleness index,low clay mineral content,and significant areal differences,as well as by the transformation from elasticity to plasticity,difficulty in sanding,and high mechanical and strength parameters.Simultaneously,they were accompanied by six high values of formation temperature,horizontal principal stress difference,pore pressure,fracture pressure,extension pressure,and closure pressure.The key to deep shale gas horizontal well fracturing was to improve the complexity of the hydraulic fracture network,formadequate proppant support of fracture surface,and increase the practical stimulated reservoir volume(SRV),which accompanied visual hydraulic discrete network monitoring.On this basis,we proposed several ideas to improve China’s deep shale gas development involving advanced technology systems,developing tools,and supporting technologies in shale gas exploration and development in the United States.These ideas primarily involved stimulation technologies,such as vertically integrated dessert identification and optimization,horizontal well multistage/multicluster fracturing,staged tools development for horizontal wells,fractures network morphology monitoring by microseismic and distributed optical fiber,shale hydration expansion,soak well,and fracturing fluid flow back.China initially developed the critical technology of horizontal well large-scale and high-strength volume fracturing with a core of“staged fracturing with dense cutting+shorter cluster spacing+fracture reorientation by pitching+forced-sand addition+increasing diameter perforating+proppant combination by high strength and small particle size particles”.We concluded that China should continue to conduct critical research on theories and technical methods of horizontal well fracturing,suitable for domestic deep and ultra-deep marine and marine-continental sedimentary shale,to support and promote the efficient development of shale gas in China in the future.It is essential to balance the relationship between the overall utilization degree of the gas reservoir and associated economic benefits and to localize some essential tools and supporting technologies.These findings can contribute to the flourishing developments of China’s deep shale gas.

Dynamics Analysis of Square Unit and its Combined Mechanism with Joint Clearance

The deployable mechanisms consisting of square units are widely applied in aeronautics and astronautics,biomedicine, architecture and other fields, and joint clearance in such a mechanism is unavoidable. This study is carried out to accurately investigate the dynamic property of the mechanism.Firstly,a dynamics model was built by considering the motion characteristics between elements of joint with clearances. Secondly,based on Floures contact force model and LuGre friction force model,the tangential and normal contact force of revolute pair element with clearance were calculated respectively. Finally,square combined mechanisms' dynamic analytical method considering joint clearance was investigated, and constraint renege problem was resolved by adopting Baumgarte stable constraint method in integration process.Analytical result indicates that the impact of joint clearance on dynamic property of square combined mechanism should not be neglected.

Type Synthesis of Fully Decoupled Three Translational Parallel Mechanism with Closed-Loop Units and High Stifness

In order to solve the problem of weak stifness of the existing fully decoupled parallel mechanism, a new synthesis method of fully decoupled three translational (3T) parallel mechanisms (PMs) with closed-loop units and high stifness is proposed based on screw theory. Firstly, a new criterion for the full decoupled of PMs is presented that the reciprocal product of the transmission wrench screw matrix and the output twist screw matrix of PMs is a diagonal matrix, and all elements on the main diagonal are nonzero constants. The forms of the transmission wrench screws are determined by the criterion. Secondly, the forms of the actuated and unactuated screws can be obtained according to their relationships with the transmission wrench screws. The basic decoupled limbs are generated by combination of the above actuated and unactuated screws. Finally, a closed-loop units construction method is investigated to apply the decoupled mechanisms in a better way on the high stifness occasion. The closed-loop units are constructed in the basic decoupled limbs to generate a high-stifness fully decoupled 3T PM. Kinematic and stifness analyses show that the Jacobian matrix is a diagonal matrix, and the stifness is obviously higher than that of the coupling mechanisms, which verifes the correctness of the proposed synthesis method. The mechanism synthesized by this method has a good application prospect in vehicle durability test platform.

Effects of nursing team communication and collaboration on treatment outcomes in intensive care unit patients with severe pneumonia

BACKGROUND Severe pneumonia is a common severe respiratory infection worldwide,and its treatment is challenging,especially for patients in the intensive care unit(ICU).AIM To explore the effect of communication and collaboration between nursing teams on the treatment outcomes of patients with severe pneumonia in ICU.METHODS We retrospectively analyzed 60 patients with severe pneumonia who were treated at the ICU of the hospital between January 1,2021 and December 31,2023.We compared and analyzed the respiratory mechanical indexes[airway resistance(Raw),mean airway pressure(mPaw),peak pressure(PIP)],blood gas analysis indexes(arterial oxygen saturation,arterial oxygen partial pressure,and oxygenation index),and serum inflammatory factor levels[C-reactive protein(CRP),procalcitonin(PCT),cortisol(COR),and high mobility group protein B1(HMGB1)]of all patients before and after treatment.RESULTS Before treatment,there was no significant difference in respiratory mechanics index and blood gas analysis index between 2 groups(P>0.05).However,after treatment,the respiratory mechanical indexes of patients in both groups were significantly improved,and the improvement of Raw,mPaw,plateau pressure,PIP and other indexes in the combined group after communication and collaboration with the nursing team was significantly better than that in the single care group(P<0.05).The serum CRP and PCT levels of patients were significantly decreased,and the difference was statistically significant compared with that of nursing group alone(P<0.05).The levels of serum COR and HMGB1 before and after treatment were also significantly decreased between the two groups.CONCLUSION The communication and collaboration of the nursing team have a significant positive impact on respiratory mechanics indicators,blood gas analysis indicators and serum inflammatory factor levels in the treatment of severe pneumonia patients in ICU.

Synthesization and crystallization mechanism of nano-scale γ-AlOOH with various morphologies

Nano-scale γ-AIOOH with various morphologies, such as whisker, bar, ball, and sheet, was synthesized successfully and control- lably through a facile hydrothermal method just by adjusting the pH value of the solvent. Based on the analysis of the experimental data, the growth mechanism of nano-scale γ-AlOOH in the hydrothermal process was established. It is proposed that the growth unit and the growth direction are determined by the pH value of the solution and the growth unit, respectively. One-dimensional γ-AlOOH, such as whisker and bar, is formed in lower pH ranges, while two-dimensional γ-AlOOH sueli as sheet is formed only in high pH environment following the plane expansion crystallization mechanism.

Design and Analysis of a Multi-Legged Robot with Pitch Adjustive Units

The paper proposes a novel multi-legged robot with pitch adjustive units aiming at obstacle surmounting.With only 6 degrees of freedom,the robot with 16 mechanical legs walks steadily and surmounts the obstacles on the complex terrain.The leg unit with adjustive pitch provides a large workspace and empowers the legs to climb up obstacles in large sizes,which enhances the obstacle surmounting capability.The pitch adjustment in leg unit requires as few independent adjusting actuators as possible.Based on the kinematic analysis of the mechanical leg,the biped and quadruped leg units with adjustive pitch are analyzed and compared.The configuration of the robot is designed to obtain a compact structure and pragmatic performance.The uncertainty of the obstacle size and position in the surmounting process is taken into consideration and the parameters of the adjustments and the feasible strategies for obstacle surmounting are presented.Then the 3D virtual model and the robot prototype are built and the multi-body dynamic simulations and prototype experiments are carried out.The results from the simulations and the experiments show that the robot possesses good obstacle surmounting capabilities.