Research on the Reuse of Discharged Soil from EBP Shield Tunnels in Synchronous Grouting Material

Great practical significance and engineering application value can be achieved when the large amount of discharged soil produced by EPB shield tunnels is recycled and comprehensively utilized. As one of the key processes of shield construction, synchronous grouting needs a large amount of bentonite, cement, fly ash, sand, and other materials. The research on the reuse of shield muck as synchronous grouting material is carried out based on Zhengzhou subway project. The physical properties and phase of the discharged soil from EPB shield tunnels are studied by using laboratory tests and XRD. The statistics show that the shield muck meets the performance requirements of bentonite and fine sand in synchronous grouting materials. The optimal grout ratio of the reused muck is obtained based on the optimization idea of multiobjective programming by MATLAB. Considering the combined effect of seepage field, stress field, and the timeliness of the grout, the influences of grouting pressure and the filling rate of synchronous grouting on surface settlement, plastic zone of strata, and segment deformation are analyzed by using finite difference method. The results prove that the surface settlement and segment deformation can be better controlled when the grouting pressure is at 0.18 MPa and the grouting rate is at 120%–150%.

FE Modelling and Prediction of Macrosegregation Patterns in Large Size Steel Ingots: Influence of Filling Rate

In the present work, the influence of filling rate on macrosegregation in a 40-Metric Ton (MT) ingot of a high-strength low-carbon steel was studied using finite element (FE) simulation. The modelling of the filling and solidification processes were realized with a two-phase (liquid-solid) multiscale 3D model. The liquid flow induced by the pouring jet, the thermosolutal convection, and the thermomechanical deformation of the solid phase were taken into consideration. Two filling rates were examined, representing the upper and lower manufacturing limits for casting of large size ingots made of high strength steels for applications in energy and transportation industries. The evolution of solute transport, as well as its associated phenomena throughout the filling and cooling stages, were also investigated. It was found that increasing the filling rate reduced macrosegregation intensity in the upper section, along the centerline and in the mid-radius regions of the ingot. The results were analyzed in the framework of heat and mass transfer theories, liquid flow dynamics, and macrosegregation formation mechanisms.

The Number of Frames on ECG-Gated 18F-FDG Small Animal PET Has a Significant Impact on LV Systolic and Diastolic Functional Parameters

Objectives. This study is aimed at investigating the impact of frame numbers in preclinical electrocardiogram- (ECG-) gated 18F-fluorodeoxyglucose (18F-FDG) positron emission tomography (PET) on systolic and diastolic left ventricular (LV) parameters in rats. Methods. 18F-FDG PET imaging using a dedicated small animal PET system with list mode data acquisition and continuous ECG recording was performed in diabetic and control rats. The list-mode data was sorted and reconstructed with different numbers of frames (4, 8, 12, and 16) per cardiac cycle into tomographic images. Using an automatic ventricular edge detection software, left ventricular (LV) functional parameters, including ejection fraction (EF), end-diastolic (EDV), and end-systolic volume (ESV), were calculated. Diastolic variables (time to peak filling (TPF), first third mean filling rate (1/3 FR), and peak filling rate (PFR)) were also assessed. Results. Significant differences in multiple parameters were observed among the reconstructions with different frames per cardiac cycle. EDV significantly increased by numbers of frames (353.8 ± 57.7 μl ∗ , 380.8 ± 57.2 μl ∗ , 398.0 ± 63.1 μl ∗ , and 444.8 ± 75.3 μl at 4, 8, 12, and 16 frames, respectively; ∗ P < 0.0001 vs. 16 frames), while systolic (EF) and diastolic (TPF, 1/3 FR and PFR) parameters were not significantly different between 12 and 16 frames. In addition, significant differences between diabetic and control animals in 1/3 FR and PFR in 16 frames per cardiac cycle were observed ( P < 0.005 ), but not for 4, 8, and 12 frames. Conclusions. Using ECG-gated PET in rats, measurements of cardiac function are significantly affected by the frames per cardiac cycle. Therefore, if you are going to compare those functional parameters, a consistent number of frames should be used.

Study of polymer-based adhesive mortar with higher durability

This paper deals with the study and development of polymer-based adhesive with high filling ratio of secondary raw materials and waste materials. The goal of this paper is to develop adhesive mortar with the highest filling rate of secondary raw materials and waste materials as possible while preserving very high physical-mechanical properties, including flexural and compressive strength, pull-off bond strength and abrasion resistance. High-temperature fly ash, waste slag and waste packaging glass are used in this paper as fillers. The resulting mortar shows high physical-mechanical properties, including high abrasive resistance and very high bonding strength to a large variety of building materials including concrete, steel, glass, and tiles.

Thermal Transfer Characteristics of Flat Plate Micro Heat Pipe with Copper Spiral Woven Mesh and a Copper Foam Composite Wick

The thermal efficiency limitation of the Flat-plate Micro Heat Pipe (FMHP) is a major challenge in the development of the FMHP, where the effect of wick structure and wettability on its thermal performance is studied to improve the thermal efficiency of the FMHP. In this work, a copper spiral woven mesh and copper foam Composite Wick FMHP (CW-FMHP) is designed based on the conventional Copper Foam Wick FMHP (CFW-FMHP), and its thermal performance is analyzed regarding the wick structure and internal gas–liquid two-phase flow characteristics. An oxidized copper spiral woven mesh and copper foam Composite Wick FMHP (OCW-FMHP) has been further developed through the modification of composite wick wettability. The performance tests are carried out with the thermal transfer characteristics of CW-FMHP, OCW-FMHP, and CFW-FMHP under different filling rates and different thermal powers. The experimental results show that the thermal transfer performance of CW-FMHP reaches the optimal under a liquid filling rate of 150%, where the maximum thermal power is 15.7 W, 35.3% higher than that of the CFW-FMHP under the same filling rate. Moreover, the dynamic response characteristics of the CW-FMHP are significantly improved. The thermal resistance of the CW-FMHP is 0.48 ∘C/W under the filling rate of 150% at the thermal power of 10 W with a reduction of 9.4% compared to the CFW-FMHP under the same condition. Furthermore, the optimal filling rate for OCW-FMHP is lower compared with the CW-FMHP. The maximum thermal power of OCW-FMHP increases to 17.8 W while the thermal resistance reduces to 0.34 ∘C/W under the liquid filling rate of 140%. This implies that the composite wick structure designed in this work can improve the thermal transfer performance of the FMHP, and the composite wick with wettability modification is more effective regarding both thermal resistance and maximum thermal power.

Experimental study on the heat transfer performance of a stainless-steel heat pipe with sintered fiber wick

A kind of stainless-steel heat pipe with sintered fiber wick is investigated with the aim to improve the heat dissipation when it is used in spent fuel pool in nuclear power plant. The effects of test angle, porosity and the filling rate on the heat transfer performance of the heat pipe are studied. At test angle 90°, the permeability plays an important role on the power limit since gravity can provide the necessary driving force. Larger porosity involves with poor heat conductivity although it results in better permeability. When test angle is zero gravity is no longer the driving force. In this case, the evaporation section can still avoid dry burning because part of the evaporation section is dipped in the deionized water. Therefore, permeability and filling ratio are two important factors influencing the power limit. Filling rate determines the vapor flowing space. When test angle is smaller than zero, gravity becomes resistance force. Then the lag tension and the filling rate exert greatest influence on the performance of the heat pipe. Smaller porosity corresponds to smaller contact angle.

Optimization of Tool Geometric Parameters For a Small Fluteless Forming Tap (FFT)

A small blind internal thread (SBIT) is used to firmly fasten some functional components to the cover of 3C electronic products. The small internal thread is made in a blind hole using a fluteless forming tap (FFT) that does not produce chips. However, the four geometric parameters (tool width (W), tooth root diameter (D2), front-end diameter (Df) and tooth angle (θ)) for the FFT affect the thread filling rate (f) and the minimum torque (T) for the tapping process. This study reports a Box-Behnken design (BBD) using DEFORM-3D (finite element model) and MINITAB (regression analysis) software to tap 7075-T6 aluminum alloy using a small FFT to achieve a repeatable thread filling rate and minimum torque. The experimental results show that the BBD accurately predicts and simulate the thread filling rate for tapping 7075-T6 aluminum alloy. The modelling software and the experimental design for this study can be used to optimize the design of tools that are used in industrial production.

Regulation of subsoiling tillage on the grain filling characteristics of maize varieties from different eras

Grain filling is the key stage for achieving high grain yield. Subsoiling tillage, as an effective conservation tillage, has been widely used in the maize planting region of China. This study was conducted to explore the effects of subsoiling on the grain filling characteristics of maize varieties of different eras. Five typical maize varieties from different eras (1970s, 1980s, 1990s, 2000s and 2010s) were used as experimental materials with two tillage modalities (rotation tillage and subsoiling tillage). The characteristic parameters (Tmax: the time when the maximum grouting rate was reached, Wmax: the grain weight at the maximum filling rate, Rmax: the maximum grouting rate, P: the active grouting stage, Gmean: the average grouting rate; A: the ultimate growth mass) and rate parameters (T1: the grain filling duration of the gradually increasing stage, V1: the average grain filling rate of the gradually increasing stage, T2: he grain filling duration of the rapidly increasing stage, V2: the average grain filling rate of the rapidly increasing stage, T3: the grain filling duration of the slowly increasing stage, V3: the average grain filling rate of the slowly increasing stage) of grain filling of two tillage modalities were analyzed and compared. The results showed that the filling parameters closely correlated with the 100-kernel weight were significantly different among varieties from different eras, and the grain filling parameters of the 2010s variety were better than those of the other varieties, the P and Tmax prolonged by 4.06–19.25%, 5.88–27.53% respectively, the Rmax and Gmean improved by 5.68–14.81%, 4.76–12.82% and the Wmax increased by 10.14–32.58%. Moreover, the 2010s variety helped the V2 and V3 increase by 6.49–13.89%, 4.55–15.00%. In compared with rotation tillage, the grain yield of maize varieties from different eras increased by 4.28–7.15% under the subsoiling condition, while the 100-kernel weight increased by 3.53–5.06%. Under the same contrast conditions, subsoiling improved the Rmax, Wmax and Gmean by 1.23–4.86%, 4.01–5.96%, 0.25–2.50% respectively, delayed the Tmax by 4.04–5.80% and extended the P by 1.19–4.03%. These differences were major reasons for the significant increases in 100-kernel dry weight under the subsoiling condition. Moreover, subsoiling enhanced the V2 and V3 by 0.70–4.29%, 0.00–2.44%. The duration of each filling stage and filling rate of maize varieties from different eras showed different responses to subsoiling. Under the subsoiling condition, the average filling rate of the 1970–2010s varieties were improved by 1.18%, 0.34%, 0.57%, 1.57% and 2.69%. In the rapidly increasing period, the grain filling rate parameters of the 2010s variety were more sensitive to subsoiling than those of the other varieties. The rapidly increasing and slowly increasing period are the key period of grain filling. Since the 2010s variety and subsoiling all improve the grain filling rate parameters of two periods, we suggest that should select the variety with higher grain filling rate in the rapidly increasing and slowly increasing period, and combine subsoiling measures to improve the grain filling characteristic parameters of maize in production, so as to achieve the purpose of increasing 100 grain weight and yield.

EP.TU.270Improving Treatment Escalation Plan (TEP) Completion Rate for General Surgical Patients

Aims Treatment Escalation Plan (TEP) is essential for recognition of patients’ ceiling for care in the event of clinical deterioration. It should be clearly documented to ensure continuity of care, especially during Covid-19 pandemic. This audit aims to evaluate and improve the TEP filling rate for general surgical patients. Methods A prospective data collection was performed for one week in July 2020 in general surgical wards. Data on patients’ gender, age, presence of DNACPR form and date of TEP completion were collected from patients’ clinical notes. Data was analysed using SPSS statistic software. Educational posters were displayed in the ward and presentation was done to emphasise the importance of TEP documentation. Second audit cycle was done in August 2020 to assess for improvement in TEP filling rate. Results In the first cycle, 60 patients were included with a mean age of 60. Only 11.7% patients had TEP form filled in with a mean delay of 2.7 days since admission. In the second cycle, 57 patients were included with a mean age of 66. 28.1% patients had TEP form documented with a mean delay of 1.7 days. This has shown a 140% improvement in completion rate of TEP form and 59% reduction in the delay in TEP documentation. Conclusions TEP is essential to ensure that patients received optimal care when their condition deteriorate. Simple intervention such as educational posters will help to improve the TEP completion rate. However, continuous auditing is required to ensure improvement in TEP documentation for surgical patients.

Key role of left ventricular untwisting in endurance cyclists at onset of exercise

The rise in oxygen consumption during the transition from rest to exercise is faster in those who are endurance-trained than those who have sedentary lifestyles, partly due to a more efficient cardiac response. However, data regarding this acute cardiac response in trained individuals are limited to heart rate (HR), stroke volume and cardiac output. Considering this, we compared cardiac kinetics, including left ventricular (LV) strains and twist/untwist mechanics, between endurance-trained cyclists and their sedentary counterparts. Twenty young, male, trained cyclists and 23 untrained participants aged 18-25 years performed five similar constant workload exercises on a cyclo-ergometer (target HR: 130 bpm). During each session, LV myocardial diastolic and systolic linear strains, as well as torsional mechanics, were assessed using speckle-tracking echocardiography. Cardiac function was evaluated every 15s during the first minute and every 30s thereafter, until 240s. Stroke volume increased during the first 30-45s in both groups, but to a significantly greater extent in trained cyclists (31% vs 24%). Systolic parameters were similar in both groups. Transmitral peak filling velocity and peak filling rate responded faster to exercise and with greater amplitude in trained cyclists. Left ventricular filling pressure was lower in the former, while LV relaxation was greater, but only at the base of the left ventricle. Basal rotation and peak untwisting rate responded faster and to a greater extent in the cyclists. This study provides new mechanical insights into the key role of LV untwisting in the more efficient acute cardiac response of endurance-trained athletes at onset of exercise.