Effects of working conditions on the operating characteristics of an injection system applied on CNG fueled vehicles

A model-based study is conducted to examine the operating characteristics of an injection system applied on CNG fueled vehicles. This injection system is a combination of an electric pressure regulator, a rail tube, and a solenoid injector. The electric pressure regulator has a great potential to be widely used in injection systems of natural gas-fueled engines due to its flexible operation, which can help to improve the engine performance and reduce emission. This paper presents a simulation study using mathematical models to describe and analyze the operating characteristics of the gaseous fuel injection system, in which models of electric pressure regulator, solenoid fuel injector, and control model for electric pressure regulator are presented. The simulation results are compared with experimental data to validate the simulation models. Effects of working conditions, including coil resistance of the electric pressure regulator, inlet gas pressure, and set pressure in the rail tube, on the operating characteristics of the gaseous fuel injection system are investigated. Simulation results show that when the coil resistance of the electric pressure regulator is increased from 3.1 Ω to 4.1 Ω, the maximum fluctuation of the controlled gas pressure in the rail tube is reduced from 0.017 to 0.012 MPa, respectively. By decreasing the inlet gas pressure of the electric pressure regulator from 2.5 to 2.3 MPa, the controlled gas pressure in the rail tube is more stable with the maximum fluctuation significantly reduced from 0.012 to 0.002 MPa, respectively, which leads to stability in injection flow rate. The increase of set pressure in the rail tube from 0.5 to 0.7 MPa can help to improve the stability of the controlled gas pressure in the rail tube with the maximum fluctuation respectively reduced from 0.002 to 0.001 MPa.

Rainfall in Bangladesh

Rainfall is the important climatic parameter on which the agriculture and economic condition of Bangladesh depends. For this reason, the scenario of rainfall throughout the country was illustrated briefly in this paper. Secondary data which were annual rainfall data of 34 stations were mainly used for this study, and these data were collected from BBS (Bangladesh Bureau of Statistics) between 2007 and 2019. The data were analyzed and visualized with the aid of Excel. However, the highest rainfall almost 5944 mm was recorded in Sylhet during the year 2017, and the lowest was 792 mm in Rajshahi in 2010. On the contrary, the minimum fluctuation of rainfall was observed in Mongla, whereas, the maximum fluctuation was found in Sylhet.

Comparative Study between Open Surgical Drainage and Closed Technique of Percutaneous Aspiration under Image Guidance for Management of Breast Abscess

Background: The conventional surgical management of breast abscesses consists of an incision taken over the point at which there is maximum fluctuation (or pain) and breaking of the abscess septa by digits. Now antibiotics and repeated abscess aspiration under USG guidance is new minimally invasive method which is on rise Objectives: To study the outcome of open technique of breast abscess management. To study the outcome of closed technique of breast abscess management. To compare the outcome of open v/s closed technique of surgical management of breast abscess. Methodology: Sample will be divided into two groups and type of treatment i.e open incision and drainage or percutaneous aspiration under guidance will be decided randomly by chit system. Expected Results: Feasibility and outcome of Percutaneous drainage is better than incision and drainage Conclusion: First line management of Breast abscess will soon be percutaneous drainage under USG guidance.

GIS-based mapping of water-level fluctuations (WLF) and its impact on groundwater in an Agrarian District in Tamil Nadu, India

This study describes the results of groundwater table variation in Thanjavur District before and after the monsoon seasons. Groundwater-level data acquired by the field measurement and the elevation data have been obtained from the topographic survey. Groundwater is the major source for different sectors in this region, and the major portion was used for irrigation. The impacts of geology, soil types, topographic elevation, land-use changes were critically analyzed and identified that these factors are controlling the infiltration capacity. The maximum fluctuation in the water table was 2 m below the ground level; still, 50% of the study area is under threat of overexploitation. This is projecting to a severe shortage in water supply soon. Groundwater quality is threatening by the saline intrusion in the coastal region, and the irrigation return flows inland. The spatial variation maps were useful in visualizing the seasonal water level and fluctuation in Thanjavur. A proper monitoring system, efficient irrigation practices, and effective groundwater recharge structures are recommended.

Fiber-optic Fabry–Perot temperature sensor based on the ultraviolet curable glue-filled cavity and two-beam interference principle

An ultraviolet curable glue (UCG)-filled microprobe Fabry–Perot fiber temperature sensor, which based on the two-beam interference principle, is proposed and fabricated. In the range of 25.7–250 °C, the average sensitivity and average linear correlation coefficient of the sensor are −41.69 pm/°C and 0.98558, respectively. Under the same temperature, the maximum fluctuation (0.56 pm) of the trough’s wavelength and the standard error (0.0023 ± 0.04%) are obtained. The proposed interferometer exhibits excellent stability and has a potential application in the field of temperature monitoring.

Speed Sensorless Control of Linear Ultrasonic Motors Based on Stator Vibration Amplitude Compensation

In some applications of linear ultrasonic motors (LUSMs), not installing speed/position sensors can reduce the size and cost of the system, changes in load will cause fluctuations in the speed of the LUSM. To eliminate the influence of load changes on speed, a speed sensorless control scheme based on stator vibration amplitude compensation (SSCBVC) is proposed. This scheme is implemented under the framework of the stator vibration amplitude-based speed control (VBSC) and frequency tracking. Based on the stator vibration amplitude-speed and the output force-speed curves of the LUSM, the relationship between the load changes and stator vibration amplitude (SVA) to be compensated is established, realizing a speed sensorless control of the LUSM under variable load conditions. The experimental results show that the maximum fluctuation of the speed is about 2.2% when the output force changes from 0 to 6 N with SSCBVC. This scheme can effectively reduce the influence of load changes on the speed of the LUSM without using speed/position sensors.

Effect of Blade Outlet Angle on Radial Force of Marine Magnetic Drive Pump

To research the effects of the blade outlet angle on the performance and the radial force of the marine pump, the unsteady numerical simulation of the four different models is carried out. The radial forces on the impeller and the blades are obtained under different flow rate conditions. The time and frequency domain characteristics of radial resultant force on the impeller and the blades are analyzed and those of the impeller torque are researched. The results show that the radial forces of the impeller and the blades increase with the increase of the blade outlet angle at the same flow rate. With the same blade outlet angle, the radial forces decrease with the increase of the flow rate. The roundness of radial force vector diagram becomes more obvious with the decrease of the blade outlet angle. The root mean square (RMS) of radial force on the blades is about 30% of that on the impeller. The main frequency of radial force on the impeller and the blades is the axial passing frequency (APF), and that of impeller torque is the blade passing frequency (BPF), and there are peaks at the blade frequency multiplier. At the same flow rate, the main frequency and maximum fluctuation amplitudes on the impeller and the blades increase with the increase of the blade outlet angle. Meanwhile, the impeller torque increases with the increase of the blade outlet angle. With the same blade outlet angle, the main frequency, maximum fluctuation amplitudes, and the impeller torque decrease with the increase of the flow rate. The amplitude difference decreases with the increase of the flow rate. The blade outlet angle has an obvious greater influence on the radial forces and fluctuation at the small flow rate. The vibration test shows that the vibration intensities of model 25 and model 35 are less than 2.5 mm/s, and the vibration intensity of model 25 is about 0.2 mm/s less than that of model 35.

Thermal Fluctuation Characteristics around a Nanosecond Pulsed Dielectric Barrier Discharge Plasma Actuator using a Frequency Analysis based on Schlieren Images

A thermal fluctuation driven by a burst plasma discharge is experimentally investigated using a frequency analysis based on the Schlieren images. The burst plasma discharge is controlled by an interval frequency fint = 200 Hz and a pulse frequency fB = 3.6 kHz as well as the duration time of the burst event: Ton. A burst feature is defined as a burst ratio BR = Ton/(1/fint). The burst plasma discharge generates a burst-induced hot plume growing above a ground electrode. In a high burst ratio, which is BR = 0.45 and 0.57, the burst-induced hot plume is formed as a wave thermal pattern that is mainly fluctuated at the interval frequency of 200 Hz. Additionally, a maximum fluctuation spot of 200 Hz appears near the edge of an exposed electrode in a low burst ratio, whereas it moves towards the ground electrode in the high burst ratio. The possible scenario is that a relatively strong ionic wind and/or an induced jet generated in the high burst ratio might cause the movement of the maximum fluctuation spot.

Complexity Synchronization of Energy Volatility Monotonous Persistence Duration Dynamics

A new concept named volatility monotonous persistence duration (VMPD) dynamics is introduced into the research of energy markets, in an attempt to describe nonlinear fluctuation behaviors from a new perspective. The VMPD sequence unites the maximum fluctuation difference and the continuous variation length, which is regarded as a novel indicator to evaluate risks and optimize portfolios. Further, two main aspects of statistical and nonlinear empirical research on the energy VMPD sequence are observed: probability distribution and autocorrelation behavior. Moreover, a new nonlinear method named the cross complexity-invariant distance (CID) FuzzyEn (CCF) which is composed of cross-fuzzy entropy and complexity-invariant distance is firstly proposed to study the complexity synchronization properties of returns and VMPD series for seven representative energy items. We also apply the ensemble empirical mode decomposition (EEMD) to resolve returns and VMPD sequence into the intrinsic mode functions, and the degree that they follow the synchronization features of the initial sequence is investigated.

EFFECT OF STENOSIS SEVERITY ON SHEAR-INDUCED DIFFUSION OF RED BLOOD CELLS IN CORONARY ARTERIES

In large blood vessels, migration of red blood cells (RBCs) affects the concentration of platelets and the transport of oxygen to the arterial endothelial cells. In this work, we investigate the locations where hydrodynamic diffusion of RBCs occurs and the effects of stenosis severity on shear-induced diffusion (SID) of RBCs, concentration distribution and wall shear stress (WSS). For the first time, multiphase mixture theory approach with Phillips shear-induced diffusive flux model coupled with Quemada non-Newtonian viscosity model has been applied to numerically simulate the RBCs macroscopic behavior in four different degrees of stenosis (DOS) geometries, viz., 30%, 50%, 70% and 85%. Considering SID of RBCs, the calculated average WSS increased by 77.70% which emphasises the importance of SID in predicting hemodynamic parameters. At the stenosis throat, it was observed that 85% DOS model had the lowest concentration of RBCs near the wall and highest concentration at the center. For the stenosis models with 70% and 85% DOS, the RBC lumen wall concentration at the distal section of stenosis becomes inhomogeneous with the maximum fluctuation of 1.568%. Finally, the wall regions with low WSS and low RBC concentrations correlate well with the atherosclerosis sites observed clinically.