Search Results (8)

The hydrodynamics characteristics of artificial water diversion canals with long-distance and inter-basin multi-stage sluice gate regulations are prone to sudden increases and decreases, and sluice gate discharge differs from that of natural rivers. Research on the change characteristics of hydrological elements in artificial canals under the control of sluice gates is lacking, as are scientifically accurate calculations of sluice gate discharge. Therefore, addressing these gaps in long-distance artificial water transfer is of great importance. In this study, real-time operation data of 61 sluice gates, pertaining to the period from May 2019 to July 2021, including data on water levels, flow discharge, velocity, and sluice gate openings in the main canal of the Middle Route of the South-to-North Water Diversion Project of China, were analyzed. The discharge coefficient of each sluice gate was calculated by the dimensional analysis method, and the unit-width discharge was modeled as a function of gate opening ($e$), gravity acceleration ($g$), and energy difference ($H$). Through logarithmic transformation of the Buckingham Pi theorem-derived equation, a linear regression model was used. Data within the relative opening orifice flow regime were selected for fitting, yielding the discharge coefficients and stage–discharge relationships. The results demonstrate that during the study period, the water level, discharge, and velocity of the main canal showed an increasing trend year by year. The dimensional analysis results indicate that the stage–discharge response relationship followed a power function ($Q\propto {(\frac{H}{e})}^{constant}$) and that there was a good linear relationship between $l{g}^{(\frac{H}{e})}$ and $l{g}^{(\frac{K}{e})}$ (R² > 0.95, $K={(q^2/g)}^{1/3}$). By integrating geometric, operational, and hydraulic parameters, the proposed method provides a practical tool and a scientific reference for analyzing sluice gates’ regulation and hydrological response characteristics, optimizing water allocation, enhancing ecological management, and improving operational safety in long-distance inter-basin water diversion projects. Full article

A hydrogel system with the ability to control the delivery of multiple drugs has gained increasing interest for localized disease treatment and tissue engineering applications. In this study, a triple-drug-loaded model based on a core/shell fiber system (CFS) was fabricated through the co-axial 3D printing of hydrogel inks. A CFS with drug 1 loaded in the core, drug 2 in the shell part, and drug 3 in the hollow channel of the CFS was printed on a rotating collector using a co-axial nozzle. Doxorubicin (DOX), as the model drug, was selected to load in the core, with the shell and channel part of the CFS represented as drugs 1, 2, and 3, respectively. Drug 2 achieved the fastest release, while drug 3 showed the slowest release, which indicated that the three types of drugs printed on the CFS spatially can achieve sequential triple-drug release. Moreover, the release rate and sustained duration of each drug could be controlled by the unique core/shell helical structure, the concentration of alginate gels, the cross-linking density, the size and number of the open orifices in the fibers, and the CFS. Additionally, a near-infrared (NIR) laser or pH-responsive drug release could also be realized by introducing photo-thermal materials or a pH-sensitive polymer into this system. Finally, the drug-loaded system showed effective localized cancer therapy in vitro and in vivo. Therefore, this prepared CFS showed the potential application for disease treatment and tissue engineering by sequential- or stimulus-responsively releasing multi-drugs. Full article

Traditional open surgery complications are typically due to trauma caused by accessing the procedural site rather than the procedure itself. Minimally invasive surgery allows for fewer complications as microdevices operate through small incisions or natural orifices. However, current minimally invasive tools typically have restricted maneuverability, accessibility, and positional control of microdevices. Thermomagnetic-responsive microgrippers are microscopic multi-fingered devices that respond to temperature changes due to the presence of thermal-responsive polymers. Polymeric devices, made of poly(N-isopropylacrylamide-co-acrylic acid) (pNIPAM-AAc) and polypropylene fumarate (PPF), self-fold due to swelling and contracting of the hydrogel layer. In comparison, soft metallic devices feature a pre-stressed metal bilayer and polymer hinges that soften with increased temperature. Both types of microdevices can self-actuate when exposed to the elevated temperature of a cancerous tumor region, allowing for direct targeting for biopsies. Microgrippers can also be doped to become magnetically responsive, allowing for direction without tethers and the retrieval of microdevices containing excised tissue. The smaller size of stimuli-responsive microgrippers allows for their movement through hard-to-reach areas within the body and the successful extraction of intact cells, RNA and DNA. This review discusses the mechanisms of thermal- and magnetic-responsive microdevices and recent advances in microgripper technology to improve minimally invasive surgical techniques. Full article

This study considers a multi-stage sleeve control valve with different opening degrees. The flow capacity of the numerical model is calculated using the actual working conditions of the control valve in a nuclear power plant as a baseline. A flow resistance test bench is then used to measure the flow capacity under each opening degree, and the flow characteristic curve is plotted to verify the accuracy of the numerical model. Based on CFX software simulations of different opening speeds, pressures, turbulent kinetic energy clouds, and set detection curves, analysis of the flow characteristics of the multi-stage sleeve valve with high parameters shows that, with an increase in the degree of opening, the valve speed will also increase. However, the speed at the socket orifice is slightly different, exhibiting a higher opening in the middle and lower openings on both sides. A maximum speed of 792.4 m/s is found in the 40% valve orifice. A maximum value of the turbulent kinetic energy of 1.4 × 10 ⁴m²/s² occurs in the throttle hole of the valve seat with an opening of 80%. The source of the aerodynamic noise is obtained in this study, which is of great significance to the decompression and noise reduction in multi-stage sleeve valves. Full article

This study is an experimental study corresponding to an analytical study presented previously, where a scaled-down model was built and tested in a water tank by following the size and shape of the structure applied in the analytical study. In this study, a wave energy converter of an oscillating water column (OWC) system is integrated with the infrastructure of a jacket-type offshore platform applied to an offshore wind turbine system. The purpose is to conduct a combination system through the simultaneous utilization of both wind power and wave power so that sustainable energy can be maximized. During the analytical study’s analysis, the airflow response and the converting efficiency of wave energy from an OWC system integrated with an offshore template structural system were evaluated. By following the analytical study’s analysis, the performance of all the systems is tested, including the airflow velocity, pneumatic power, and the converting efficiency of the power from waves. The experimental data are analyzed and discussed in terms of the variations of the OWC system’s geometrical parameters. The parameters under consideration include the exhale orifice-area of airflow, gate-openings of inflow water, and the submerged chamber depth. It is found from the experimental results that, through the comparison between the experimental data and the analytical results, the results of the analytical study’s analysis are countable, and an open sea OWC system can be successfully applied to the template structure of offshore wind power infrastructure as a secondary generating system for the multi-purpose utilization of the structure. Full article

This study is focused on the wave energy converter of an oscillating water column (OWC) system that is integrated with a jacket type infrastructure applied for an offshore wind turbine system. In this way, electricity generation by both wind power and wave power can be conducted simultaneously to maximize the utilization of sustainable energy. A numerical analysis was performed in this research to model and simulate the airflow response and evaluate the converting efficiency of wave energy from an OWC system integrated with an offshore template structural system. The performance of the system including the generating airflow velocity, air-pressure in the chamber, generating power and then the converting efficiency of power from waves are all analyzed and discussed in terms of the variations of the OWC system’s geometrical parameters. The parameters under consideration include the exhale orifice-area of airflow, gate-openings of inflow water and the submerged chamber depth. It is found that from the analytical results the performance of the OWC wave energy converter is influenced by the dimensional parameters along with the design conditions of the local environment. After a careful design based on the in-situ conditions including water depth and wave parameters, an open OWC system can be successfully applied to the template structure of offshore wind power infrastructure as a secondary generating system for the multi-purpose utilization of the structure. Full article

This article contains the results of experimental studies of a multi-opening orifice with substitute constriction factor of β = 0.5 (m = 0.25), mounted in a DN50 hydraulic measuring flume. Flow measurements were taken from a progressing turbulent flow within Reynolds numbers (Re = 4700–19,500). Based on conducted experimental data, flow characteristics, and discharge coefficient C characteristics were determined. Relative expanded uncertainty of determining a discharge coefficient C was estimated within the changes of volume flow q_v from 0.35 to 0.68 dm³/s, based on rules from the GUM international standard. The value, determined from uncertainty analysis, did not exceed 1.25% within the changes of Reynolds numbers 9800 ≤ Re ≤ 19,500. Full article

Airflow into stairwells due to stack effect is a concern affecting fire safety, energy performance, and indoor air quality. Stack effect in tall buildings can create significant pressure differentials in vertical shafts when differences in outdoor and indoor temperature exist. The pressure differentials drive air through openings or gaps in walls and floors. Vertical shafts, consisting of stairs and elevators, may transport significant volumes of air. During heating season, this results in the infiltration of cold air at lower floors and the exhaust of warm air on the upper floors. Correspondingly, it results in the spread of air and potential contaminants within the building. Stack effect driven airflow will change according to size and distribution of leakage paths. The size of leakage areas can be approximated by a cross-sectional area of an orifice that would allow equivalent flow. This leakage area is dependent on construction material, workmanship, and even operation, as openings from windows and doors equate to large orifices. A building’s composition of these leakage areas can greatly impact the effective area and airflow. The effect of openings from stairwell doors can change the Neutral Pressure Plane location (NPP), altering airflow patterns within a building. This paper investigates the influence of effective area on airflow within stairwells for multi-unit residential buildings (MURB) due to stack effect. A range of parameters reflective of industry standards are evaluated using network modeling and computational fluid dynamics (CFD). Parametric analysis is used to determine the sensitivity to which they affect airflow between building and stairwells. The effect of airflow within vertical shafts has consequences on indoor air quality (IAQ) and smoke spread, energy efficiency, and thermal comfort. The benefit of reducing leakage in buildings can be understood by comparing the quantity and patterns in airflow in and out of stairwells. Improving air tightness of the building envelope or vertical shafts can have a significant impact on airflow. Full article