scholarly journals Sources of the Measurement Error of the Impact Pressure in Sloshing Experiments

2019 ◽  
Vol 7 (7) ◽  
pp. 207
Author(s):  
Dong Hwi Kim ◽  
Eun Soo Kim ◽  
Sung-chul Shin ◽  
Sun Hong Kwon
Keyword(s):  
Integrated Circuit ◽  
Measurement Errors ◽  
High Speed ◽  
Pressure Sensors ◽  
Pressure Measurements ◽  
Sensor Surface ◽  
Experimental Conditions ◽  
Surface Conditions ◽  
Peak Pressures ◽  
The Impact

Sloshing experiments have increasingly received academic attention. Understanding the measurement errors in the sloshing impact pressures is an important parts of the sloshing experiments since these errors, which arise from experimental conditions, affect the subsequent results. As part of the research on the sources of the measurement errors, focused on the effects of surface conditions of pressure sensors on the measurement of impact pressures. Thirty-six integrated circuit piezoelectric pressure sensors were placed on the upper surfaces of a two-dimensional tank to measure the sloshing impact pressures under surge or pitch motions. For each motion, the experimental conditions were divided in two based on whether the surfaces of the sensors were dry or wet. The peak pressures of each test were measured as twenty repeated experiments to ensure reliability. The flow in the tank was visualized using a high-speed camera to observe and analyze macroscopic and microscopic phenomena along the sensor surface. Thermal shock effects were confirmed by varying the experimental temperature and that of the sensor surface. The effects of the wet surface and droplets formed on the sensor surface on pressure measurements are discussed.

Investigations of Reduction Effect of Vertical Wall on Dam-Break-Simulated Tsunami Surge Exerted on Wharf Piles

2018 ◽  
Vol 12 (02) ◽  
pp. 1840006 ◽  
Author(s):  
Cheng Chen ◽  
Bruce W. Melville ◽  
N. A. K. Nandasena
Keyword(s):  
High Speed ◽  
Preliminary Investigation ◽  
Vertical Wall ◽  
Pressure Sensors ◽  
Time History ◽  
Dam Break ◽  
Reservoir System ◽  
Reduction Effect ◽  
The Impact ◽  
Surge Height

For a preliminary investigation of the impact of a tsunami surge on wharf piles, a tsunami flume was built in a laboratory, and a dam break flow was generated by a gate-reservoir system to simulate a tsunami surge. In addition, a vertical wall was installed in front of the wharf model so that its effect in reducing tsunami load could be studied. Five different tsunami surge strengths were generated by this gate-reservoir system. Wave transducers were used in the test flume to capture surge heights and velocities, and hence the surge front profiles, for different surge strengths. High-speed video cameras (210 frames per second) were used to record the flow motion of the tsunami surge, and pressure sensors (1000[Formula: see text]Hz in frequency) were used to capture the time histories of the tsunami pressure on the wharf piles. Four stages of tsunami surge motions were observed by this high-speed camera. Accordingly, the pressure time history can be divided into three phases. In our experimental range, pressures were influenced by surge height and wall height, but not by the wall position. Based on the dimensionless experimental data (pile heights, surge heights, vertical wall heights, and surge pressures), equations for estimating tsunami loads on wharf pile are proposed, expressing surge front (peak impact) pressure and quasi-steady pressure as functions of surge height, wall height, and pile height.

scholarly journals Study on the Impact of Lead Sidewall Solder Coverage and Corner Lead Size on Joint Reliability

2021 ◽  
pp. 62-69
Author(s):  
Jefferson Talledo
Keyword(s):  
Solder Joint ◽  
Integrated Circuit ◽  
High Speed ◽  
Printed Circuit Board ◽  
Circuit Board ◽  
Element Analysis ◽  
Solder Joint Reliability ◽  
Joint Reliability ◽  
Solder Fatigue ◽  
The Impact

Solder joint reliability is very important to ensure that an integrated circuit (IC) semiconductor package is functional within its intended life span as the solder joint establishes electrical connection between the IC and the printed circuit board (PCB). Solder fatigue failure or crack under thermal cycling is one of the common problems with board-mounted packages. There are several factors or package characteristics that have impact on solder fatigue life like package size and material properties of the package components. This paper presents a thermo-mechanical modeling of a leadframe-based semiconductor package to study the impact of lead sidewall solder coverage and corner lead size on the solder joint reliability. Finite element analysis (FEA) technique was used to calculate the solder life considering 50% and 100% package lead sidewall solder coverage as well as smaller and larger critical corner leads of the package. The results of the analysis showed that higher lead sidewall solder coverage and larger lead could significantly increase solder life. Therefore, ensuring lead sidewall solder wettability to have higher solder coverage is beneficial. The study also reveals that packages with side wettable flanks are not only enabling high speed automated optical inspection required for the automotive industry, but they are also providing improved solder joint reliability.

scholarly journals Meander-DGS Effect on Electromagnetic Bandgap Structure for Power/Ground Noise Suppression in High-Speed Integrated Circuit Packages and PCBs

Electronics ◽  
2022 ◽  
Vol 11 (2) ◽  
pp. 211
Author(s):  
Myunghoi Kim
Keyword(s):  
Slow Wave ◽  
Integrated Circuit ◽  
Analytical Method ◽  
High Speed ◽  
Noise Suppression ◽  
Cutoff Frequency ◽  
Closed Form Expression ◽  
Electromagnetic Bandgap ◽  
Ground Noise ◽  
The Impact

In this paper, we present the impact of a meander-shaped defected ground structure (MDGS) on the slow-wave characteristics of a lowest-order passband and a low cutoff frequency of the first stopband of an electromagnetic bandgap (EBG) structure for power/ground noise suppression in high-speed integrated circuit packages and printed circuit boards (PCBs). A semi-analytical method is presented to rigorously analyze the MDGS effect. In the analytical method, a closed-form expression for a low cutoff frequency of the MDGS-EBG structure is extracted with an effective characteristic impedance and a slow-wave factor. The proposed analytical method enables the fast analysis of the MDGS-EBG structure so that it can be easily optimized. The analysis of the MDGS effect revealed that the low cutoff frequency increases up to approximately 19% while comparing weakly and strongly coupled MDGSs. It showed that the miniaturization of the MDGS-EBG structure can be achieved. It was experimentally verified that the low cutoff frequency is reduced from 2.54 GHz to 2.00 GHz by decreasing the MDGS coupling coefficient, which is associated with the miniaturization of the MDGS-EBG structure in high-speed packages and PCBs.

Experimental Investigation of the Green Water Loads on a Wave-Piercing Tumblehome Ship

2017 ◽  
Author(s):  
Hui Li ◽  
Bao-Li Deng ◽  
Shu-Zheng Sun ◽  
Wen-Lei Du ◽  
Hao-Dong Zhao
Keyword(s):  
Experimental Investigation ◽  
High Speed ◽  
Water Pressure ◽  
Pressure Sensors ◽  
Green Water ◽  
Strong Nonlinearity ◽  
Water Tank ◽  
Water Tank Experiment ◽  
The Impact ◽  
Ship Speed

This paper presents the results of an experimental investigation of green water loads on a wave-piercing tumblehome ship. A water tank experiment was carried out in head regular waves by using a self-propelling segmented ship model. Wave probes and pressure sensors were arranged on the bow deck along the longitudinal and transverse directions. The height of water and the impact pressure on the deck were measured and their distributions in different wave conditions studied. The motion of the water flowing on the deck was recorded by a high-speed video system. Based on the experimental results, it was found that the green water is more serious with the increase of incident wave height and ship speed. The bow shape has little effects on the occurrence of green water, but it influences the green water loads to some extent. The distribution of green water pressure is different from that of green water height due to the strong nonlinearity of green water pressure.

Impact Pressures on the Bottom of a Prismatic Planing Hull During Water Impact

2015 ◽  
Author(s):  
Carolyn Q. Judge ◽  
John A. Judge ◽  
Christine M. Ikeda
Keyword(s):  
Pressure Distribution ◽  
Structural Design ◽  
Structural Damage ◽  
High Speed ◽  
Empirical Method ◽  
Naval Academy ◽  
Water Impact ◽  
Empirical Estimates ◽  
Peak Pressures ◽  
The Impact

High-speed planing boats are subject to repeated slamming impacts, which can cause structural damage and discomfort or injury to passengers. The structural and seakeeping aspects of the design of high-speed craft are mainly determined through empirical estimates of mean and peak pressures. The primary structural guideline (Allen and Jones, 1978) relies heavily on semi-empirical criteria that are not always accurate and have limited application. The Allen and Jones guidelines provide conservative estimates leading to sufficient structural design, but do not provide enough guidance to allow strategic reduction in structural weight. Structural design depends on the hull bottom pressures while information about the magnitudes of peak pressures, time durations, and locations along the hull is generally not available. Model tests conducted at the US Naval Academy have measured bottom pressures on a prismatic planing hull geometry during operation in waves (both regular and irregular). Pressures were measured at point locations and using a two-dimensional pressure pad to examine how pressures change in both time and space during a water impact. Rosen (2005) presents a method for reconstructing the momentary pressure distribution during a hull-water impact. This method allows the measurements of a propagating pressure segment in one position of the hull at one instant in time to be associated with other positions at other instants in time (as determined from several different point pressure measurements). Morabito (2014) presents an empirical method for calculating the pressure distribution on the bottom of prismatic planing hulls. The method can be extended to the impact problem by use of an “equivalent” planing velocity. This paper compares the planing pressures predicted by Morabito's empirical method with the recreated pressure distribution determined from Rosen's method.

Impact Pressure, Void Fraction, and Green Water Velocity due to Plunging Breaking Wave Impingement on a 2D Tension-Leg Structure

2016 ◽  
Author(s):  
Wei-Liang Chuang ◽  
Kuang-An Chang ◽  
Richard Mercier
Keyword(s):  
Void Fraction ◽  
Bubbly Flow ◽  
Vertical Wall ◽  
Pressure Sensors ◽  
Density Variation ◽  
Impact Pressure ◽  
Green Water ◽  
Breaking Wave ◽  
Peak Pressures ◽  
The Impact

Violent impacts due to plunging waves impinging on a 2D tension-leg model structure were experimentally investigated in a laboratory. In the experiment, velocities, pressures, and void fraction were simultaneously measured and the relationship among them was examined. The nonintrusive bubble image velocimetry technique was employed to quantify the instantaneous bubbly flow velocities and structure motion. Pressures on the structure vertical wall above the still water level were measured by four differential pressure sensors. Additionally, four fiber optic reflectometer probes were used to measure the void fraction coincidently with the pressure sensors. With repeated simultaneous, coincident velocity, pressure and void fraction measurements, temporal evolution of the ensemble-averaged velocities, pressures, and void fraction were demonstrated and correlated. Relationship between the peak pressures and their rise time was examined and summarized in dimensionless form. Impact coefficients that relate the impact pressure with flow kinetic energy were obtained from the ensemble-averaged measurements. Finally, the impact coefficients with and without the consideration of the fluid density variation due to bubbles were examined and compared.

scholarly journals Evaluation of the Potential Electromagnetic Interference in Vertically Stacked 3D Integrated Circuits

2020 ◽  
Vol 10 (3) ◽  
pp. 748
Author(s):  
Dipesh Kapoor ◽  
Cher Ming Tan ◽  
Vivek Sangwan
Keyword(s):  
Integrated Circuits ◽  
Integrated Circuit ◽  
Electromagnetic Interference ◽  
High Speed ◽  
High Performance ◽  
Near Field ◽  
Three Dimensional ◽  
3D Ic ◽  
Three Dimensional Integrated Circuit ◽  
The Impact

Advancements in the functionalities and operating frequencies of integrated circuits (IC) have led to the necessity of measuring their electromagnetic Interference (EMI). Three-dimensional integrated circuit (3D-IC) represents the current advancements for multi-functionalities, high speed, high performance, and low-power IC technology. While the thermal challenges of 3D-IC have been studied extensively, the influence of EMI among the stacked dies has not been investigated. With the decreasing spacing between the stacked dies, this EMI can become more severe. This work demonstrates the potential of EMI within a 3D-IC numerically, and determines the minimum distance between stack dies to reduce the impact of EMI from one another before they are fabricated. The limitations of using near field measurement for the EMI study in stacked dies 3D-IC are also illustrated.

Spike and Modal Stall Inception in an Advanced Turbocharger Centrifugal Compressor

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Z. S. Spakovszky ◽  
C. H. Roduner
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Pressure Ratio ◽  
Pressure Sensors ◽  
Rotating Stall ◽  
Vaned Diffuser ◽  
Stall Inception ◽  
Compression System ◽  
The Impact ◽  
Highly Loaded

In turbocharger applications, bleed air near the impeller exit is often used for secondary flow systems to seal bearing compartments and to balance the thrust load on the bearings. There is experimental evidence that the performance and operability of highly-loaded centrifugal compressor designs can be sensitive to the amount of bleed air. To investigate the underlying mechanisms and to assess the impact of bleed air on the compressor dynamic behavior, a research program was carried out on a preproduction, 5.0 pressure ratio, high-speed centrifugal compressor stage of advanced design. The investigations showed that bleed air can significantly reduce the stable flow range. Compressor rig experiments, using an array of unsteady pressure sensors and a bleed valve to simulate a typical turbocharger environment, suggest that the path into compression system instability is altered by the bleed flow. Without the bleed flow, the prestall behavior is dominated by short-wavelength disturbances, or so called “spikes,” in the vaneless space between the impeller and the vaned diffuser. Introducing bleed flow at the impeller exit reduces endwall blockage in the vaneless space and destabilizes the highly-loaded vaned diffuser. The impact is a 50% reduction in stable operating range. The altered diffuser characteristic reduces the compression system damping responsible for long-wavelength modal prestall behavior. A four-lobed backward traveling rotating stall wave is experimentally measured in agreement with calculations obtained from a previously developed dynamic compressor model. In addition, a self-contained endwall blockage control strategy was employed, successfully recovering 75% of the loss in surge-margin due to the bleed flow and yielding a one point increase in adiabatic compressor efficiency.

Spike and Modal Stall Inception in an Advanced Turbocharger Centrifugal Compressor

2007 ◽  
Author(s):  
Z. S. Spakovszky ◽  
C. H. Roduner
Keyword(s):  
Centrifugal Compressor ◽  
High Speed ◽  
Pressure Ratio ◽  
Pressure Sensors ◽  
Rotating Stall ◽  
Vaned Diffuser ◽  
Stall Inception ◽  
Compression System ◽  
The Impact ◽  
Highly Loaded

In turbocharger applications bleed air near the impeller exit is often used for secondary flow systems to seal bearing compartments and to balance the thrust load on the bearings. There is experimental evidence that the performance and operability of highly loaded centrifugal compressor designs can be sensitive to the amount of bleed air. To investigate the underlying mechanisms and to assess the impact of bleed air on the compressor dynamic behavior, a research program was carried out on a pre-production, 5.0 pressure ratio, high-speed centrifugal compressor stage of advanced design. The investigations showed that bleed air can significantly reduce the stable flow range. Compressor rig experiments, using an array of unsteady pressure sensors and a bleed valve to simulate a typical turbocharger environment, suggest that the path into compression system instability is altered by the bleed flow. Without bleed flow, the pre-stall behavior is dominated by short wavelength disturbances, or so called ‘spikes’, in the vaneless space between the impeller and the vaned diffuser. Introducing bleed flow at impeller exit reduces endwall blockage in the vaneless space and destabilizes the highly-loaded vaned diffuser. The impact is a 50% reduction in stable operating range. The altered diffuser characteristic reduces the compression system damping responsible for long wavelength, modal pre-stall behavior. A four-lobed backward traveling rotating stall wave is experimentally measured, in agreement with calculations obtained from a previously developed dynamic compressor model. In addition, a self-contained, endwall blockage control strategy was employed, successfully recovering 75% of the loss in surge-margin due to bleed flow and yielding a 1 point increase in adiabiatic compressor efficiency.

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