Modeling Chip-Evacuation Forces in Drilling for Various Flute Geometries

2003 ◽  
Vol 125 (3) ◽  
pp. 405-415 ◽  
Author(s):  
Jeffrey C. Mellinger ◽  
O. Burak Ozdoganlar ◽  
Richard E. DeVor ◽  
Shiv G. Kapoor
Keyword(s):  
Lateral Pressure ◽  
Threshold Value ◽  
Calibration Procedure ◽  
Force Model ◽  
Critical Depth ◽  
Cross Sectional ◽  
Pressure Distributions ◽  
Flute Surface ◽  
Thrust And Torque ◽  
Validation Experiments

In this paper, a chip-evacuation force model is presented to predict the torque and thrust required to evacuate the chips during drilling for various flute geometries. The model considers the chips in the flutes as granular solids and determines the chip-evacuation thrust and torque from the normal and lateral pressure distributions in the chips that fill the flutes. The model requires two coefficients of friction that are established via a calibration procedure. The critical depth for the process is determined by setting a threshold value on the chip-evacuation torque, which is based on the onset of chip-clogging. The effectiveness of the chip-evacuation force model in determining the chip-evacuation thrust and torque and predicting the critical depth has been assessed via a set of validation experiments using both standard and parabolic drills. The parabolic drill produced lower chip-evacuation forces and increased critical depths relative to the standard drill. While the standard drill has a modestly larger effective flute cross-sectional area for most of the flute length, the parabolic drill has a significantly smaller contact area between the chips and the flute surface, which is the main reason for the superior chip-evacuation performance of the parabolic drill.

Principles of designing secondary channels along the river rhine for the benefit of ecological restoration

1995 ◽  
Vol 31 (8) ◽  
pp. 379-382 ◽  
Author(s):  
M. H. I. Schropp
Keyword(s):  
Ecological Restoration ◽  
Threshold Value ◽  
Main Channel ◽  
River Rhine ◽  
Secondary Channel ◽  
Frequency Curve ◽  
Cross Sectional ◽  
Design Value ◽  
Ecological Targets ◽  
Flow Velocities

Secondary channels present a favourable opportunity for ecological restoration of the River Rhine and its branches. However, they have to be fitted into the landscape without affecting existing interests such as inland shipping and protection against flooding. Also the ecological targets have to be met with a minimum of human interference. In this article some design principles for secondary channels are presented in which these aspects are taken into account. To avoid silting up of the secondary channel it is recommended to prevent sediment from entering the channel at all. Flow velocities have to be below the threshold value for initiation of motion of sediment, but still high enough to satisfy the ecological targets. The secondary channel discharge is a function of the maximum allowable aggradation of the main channel. Discharge and flow velocities together determine the required cross-sectional area and thus the design value of the bank slopes. In order to have flowing water in the secondary channel all year round, the thalweg level is to be chosen on the basis of the water level frequency curve of the main channel.

Pulsed Laser Melting of Amorphous Silicon: Time-Resolved and Post-Irradiation Studies

1983 ◽  
Vol 23 ◽  
Author(s):  
D. H. Lowndes ◽  
R. F. Wood ◽  
C. W. White ◽  
J. Narayan
Keyword(s):  
Pulsed Laser ◽  
Threshold Value ◽  
Dynamical Response ◽  
Cross Sectional ◽  
Time Resolved ◽  
Model Calculations ◽  
Fine Grained ◽  
Transmission Electron ◽  
Incident Laser Pulse ◽  
Thermal Melting

ABSTRACTMeasurements of the time of the onset of melting of self-implantation amorphized (a) Si, during an incident laser pulse, have been combined with modified melting model calculations and measurements of surface melt duration to demonstrate that the thermal conductivity, Ka, of a-Si is very low (≃0.02 W/cm-K). Ka is also shown to be the dominant parameter determining the dynamical response of ionimplanted Si to pulsed laser radiation; the latent heat and melting temperature of a-Si are relatively unimportant. Cross-sectional transmission electron micrographs on implantation-amorphized Si layers of several different thicknesses show that for energy densities less than the threshold value for complete annealing there are usually two distinct regions in the re-solidified a-Si, consisting of fine-grained and large-grained polycrystalline Si, respectively. The presence of the fine-grained poly-Si suggests that bulk nucleation occurs directly from the highly undercooled liquid phase. Thermal melting model calculations suggest that the nucleation temperature, Tn is ≃1200°C.

scholarly journals The Roles of Lumbar load thresholds in lifetime cumulative lifting exposure to predict disk protrusion

2019 ◽  
Author(s):  
Isabella Yu-Ju Hung ◽  
Tiffany Ting-Fang Shih ◽  
Bang-Bin Chen ◽  
Ing-Kang Ho ◽  
Saou-Hsing Liou ◽  
...  
Keyword(s):  
Final Analysis ◽  
Threshold Value ◽  
Cross Sectional Study ◽  
Optimal Threshold ◽  
Optimal Method ◽  
Cross Sectional ◽  
Women In The Workplace ◽  
Exposure Limit ◽  
Lifting Task ◽  
Lumbar Load

Abstract Background: The purpose of this study was to determine whether if a specific threshold value exists in each lifting load, the accumulation above which best predicts lumbar disk protrusion, or on the other hand, all lifting load should be accumulated. Methods: This was a cross-sectional study. Subjects with various lifetime lifting exposures were recruited. Disk protrusion was determined by magnetic resonance imaging. Lifetime cumulative lifting load was the sum of time-weighed lumbar load for each job using a biomechanical software system. For accumulation above different thresholds, predictive capabilities for disk protrusion were compared using four statistical methods. Results: A total of 252 men and 301 women were included in the final analysis. For men, 3000 Newton for each lifting task was the optimal threshold value for predicting L4-S1 disk protrusion, whereas for women, 2800 Newton was optimal. Our findings suggested that when considering lifetime exposure, including all lifting loads without defining a minimal exposure limit might not be the optimal method for predicting disk protrusion. Conclusions: The NIOSH 3400 Newton recommended limits do not appear to be optimal threshold for preventing disk protrusion. Different lifting thresholds might be applied to men and women in the workplace for safety.

scholarly journals Project SEARCH (Scanning EARs for Child Health): validating an ear biometric tool for patient identification in Zambia

2020 ◽  
Vol 4 ◽  
pp. 168
Author(s):  
Lauren Etter ◽  
Alinani Simukanga ◽  
Wenda Qin ◽  
Rachel Pieciak ◽  
Lawrence Mwananyanda ◽  
...  
Keyword(s):  
Recognition Algorithm ◽  
Patient Identification ◽  
Pattern Recognition Algorithm ◽  
Unique Identifier ◽  
Cross Sectional ◽  
Middle Income ◽  
Middle Income Countries ◽  
Image Capturing ◽  
Public Health Challenges ◽  
Validation Experiments

Patient identification in low- to middle-income countries is one of the most pressing public health challenges of our day. Given the ubiquity of mobile phones, their use for health-care coupled with a biometric identification method, present a unique opportunity to address this challenge. Our research proposes an Android-based solution of an ear biometric tool for reliable identification. Unlike many popular biometric approaches (e.g., fingerprints, irises, facial recognition), ears are noninvasive and easily accessible on individuals across a lifespan. Our ear biometric tool uses a combination of hardware and software to identify a person using an image of their ear. The hardware supports an image capturing process that reduces undesired variability. The software uses a pattern recognition algorithm to transform an image of the ear into a unique identifier. We created three cross-sectional datasets of ear images, each increasing in complexity, with the final dataset representing our target use-case population of Zambian infants (N=224, aged 6days-6months). Using these datasets, we conducted a series of validation experiments, which informed iterative improvements to the system. Results of the improved system, which yielded high recognition rates across the three datasets, demonstrate the feasibility of an Android ear biometric tool as a solution to the persisting patient identification challenge.

scholarly journals An evaluation of ultrasonic arrays for the static and dynamic measurement of wheel–rail contact pressure and area

2020 ◽  
Vol 234 (10) ◽  
pp. 1580-1593
Author(s):  
Henry Brunskill ◽  
Andy Hunter ◽  
Lu Zhou ◽  
Rob Dwyer Joyce ◽  
Roger Lewis
Keyword(s):  
Contact Pressure ◽  
Ultrasonic Transducer ◽  
Dynamic Contact ◽  
Pressure Profile ◽  
Calibration Procedure ◽  
Railway Vehicle ◽  
Profile Measurement ◽  
Two Dimensional ◽  
Cross Sectional ◽  
Contact Conditions

The interfacial contact conditions between a railway vehicle wheel and the rail are paramount to the lifespan, safety and smooth operation of any rail network. The wheel–rail interface contact pressure and area conditions have been estimated, calculated and simulated by industry and academia for many years, but a method of accurately measuring dynamic contact conditions has yet to be realised. Methods using pressure-sensitive films and controlled air flow have been employed, but both are limited. Ultrasonic reflectometry is the term given to active ultrasonics in which an ultrasonic transducer is mounted on the outer surface of a component and a sound wave is generated. This ultrasonic wave packet propagates through the host medium and reflects off the contacting interface of interest. The reflected waveform is then detected and contact area and interfacial stiffness information can be extracted from the signal using the quasi-static spring model. Stiffness can be related to contact pressure by performing a simple calibration procedure. Previous contact pressure measurement work has relied on using a focusing transducer and a two-dimensional scanning arrangement which results in a high-resolution image of the wheel–rail contact, but is limited to static loading of a specimen cut from a wheel and rail. The work described in this paper has assessed the feasibility of measuring a dynamic wheel–rail contact patch using an array of 64 ultrasonic elements mounted in the rail. Each element is individually pulsed in sequence to build up a linear cross-sectional pressure profile measurement of the interface. These cross-sectional, line measurements are then processed and collated resulting in a two-dimensional contact pressure profile. Measurements have been taken at different speeds and loads.

scholarly journals Plantar pressure distribution evaluation in children with down syndrome from 2 to 5 years old

2019 ◽  
Vol 32 ◽  
Author(s):  
Paula Silva de Carvalho Chagas ◽  
Riuraly Caroline Barreiros Fortunato Rangel ◽  
Sulamita Saile de Jesus Oliveira Dornelas ◽  
Anderson Daibert Amaral ◽  
Flávio Augusto Teixeira Ronzani ◽  
...  
Keyword(s):  
Down Syndrome ◽  
Pressure Distribution ◽  
Plantar Pressure ◽  
Cross Sectional Study ◽  
Measurement Instruments ◽  
Standing Posture ◽  
Cross Sectional ◽  
Plantar Pressures ◽  
Pressure Distributions ◽  
Plantar Pressure Distribution

Abstract Introduction: Some peculiar features of Down Syndrome (DS), such as ligament laxity, hypotonia, delay in gait acquisition, among others, may generate alterations in the distribution of plantar pressures, modifying the plantar support. Objective: To verify whether there are differences in the evaluation of plantar pressure distributions in standing posture between the measurement instruments (Baropodometer, SAPO, and Radiography). Method: This was a cross-sectional study, evaluating ten children with SD and ten children with normal development (ND), aged from two to five years old. Bio-photogrammetry, baropodometry, and foot radiography were used to assess the plantar pressure distribution. Kappa analysis was used to evaluate the agreement index between the different instruments. Results: Children with DS and ND had a higher prevalence of pronated feet in all three instruments, with poor to substantial agreement among the instruments. Conclusion: According to this study instruments, there was a greater prevalence of pronated feet in the two groups . Differences in the evaluation of the distribution of plantar pressures in the standing posture between the Baropodometer, SAPO, and radiography were observed. These instruments should be used in a complementary manner, as they propose to evaluate different aspects of the feet alignment.

scholarly journals Modeling and Distribution Laws of Drilling Force for Staggered Teeth BTA Deep Hole Drill

2018 ◽  
Vol 2018 ◽  
pp. 1-13 ◽  
Author(s):  
Xubo Li ◽  
Jianming Zheng ◽  
Yan Li ◽  
Lingfei Kong ◽  
Weichao Shi ◽  
...  
Keyword(s):  
Cutting Force ◽  
Friction Angle ◽  
Hole Drilling ◽  
Force Model ◽  
Deep Hole ◽  
Drilling Force ◽  
Cutting Force Components ◽  
Distribution Laws ◽  
Force Components ◽  
Thrust And Torque

The boring and trepanning association (BTA) deep hole drilling is a typical self-guiding machining method. The drilling force and its distribution laws along the cutting radius directly affect the stability of drilling and the quality of machined hole. Based on the oblique cutting theory, a novel drilling force model is developed to predict the thrust and torque for staggered teeth BTA deep hole drill with variable geometries. Using the constraint relationships between the cutting force components and cutting angles, combined with the measured drilling force during the drill entrance, the parameters of the model including normal shear angle, normal friction angle and shear stress involved in the cutting force coefficients along the cutting radius, and the axial and circumferential friction coefficients between the guide pads and the hole wall are obtained. The model-predicted drilling force is validated by experimental results.

Study of the Pressure Distribution between the Piston Rings in Reciprocating Compressors

2011 ◽  
Vol 383-390 ◽  
pp. 6048-6052
Author(s):  
Dian Bo Xin ◽  
Jian Mei Feng ◽  
Yan Jing Xu ◽  
Xue Yuan Peng
Keyword(s):  
Pressure Distribution ◽  
Piston Ring ◽  
Dynamic Pressure ◽  
Threshold Value ◽  
Piston Rings ◽  
Premature Failure ◽  
Root Cause ◽  
Pressure Distributions ◽  
Start Up ◽  
Set Up

Piston ring is one of the most important sealing components that can be easily damaged in reciprocating compressors. The severe non-uniformity of the pressure distribution was suggested to be the essential reason for the premature failure of the piston rings. Therefore, a test rig was set up to measure the pressure distributions as well as the build-up of the dynamic pressure difference, which could reveal the root cause for the non-uniformity of the pressure distributions. The results showed that the build-ups of the pressure differences between different rings were not simultaneous; there existed a threshold pressure, and the latter ring could work only when the pressure before the former ring reached to the threshold value. The pressure distributions were also investigated at the start-up and shut-down of the compressor, which further validated the cause of the premature failure of the first ring.

A cross-sectional study on foot loading patterns in elite soccer players of different ages

2020 ◽  
Vol 33 (6) ◽  
pp. 939-946
Author(s):  
Thilo Hotfiel ◽  
Tobias Golditz ◽  
Jessy Wegner ◽  
Johannes Pauser ◽  
Matthias Brem ◽  
...  
Keyword(s):  
Plantar Pressure ◽  
Age Groups ◽  
Relative Increase ◽  
Stress Fractures ◽  
Soccer Players ◽  
Cross Sectional ◽  
Pressure Distributions ◽  
Age Related ◽  
Loading Patterns ◽  
Foot Loading

BACKGROUND: Alterations in plantar loading patterns are risk factors for stress injuries of the lower limb, particularly of the foot and ankle. Epidemiological studies have revealed a higher incidence of soccer-related stress fractures of the fifth metatarsal (MT V) in younger athletes than in their adult counterparts. OBJECTIVE: The aim of the present study was to assess the plantar pressure distributions of members of four high-level soccer teams of different age groups to identify age-related differences in loading patterns. METHODS: A total of 65 elite soccer players were included in the study. Data were computed with sensor-loaded insoles (pedar® X system, novel Inc., Munich, Germany) while the players ran in soccer shoes. Plantar pressures for nine defined regions on the preferred and nonpreferred foot were analyzed. RESULTS: The participants consisted of 17 elite male soccer professionals from the first national league (mean 23 years, height 184 cm, weight 81 kg), 14 players from the under-21 squad (U21, 20 years, 180 cm, 75 kg), 15 players from the U17 squad (16 years, 176 cm, 69 kg) and 19 players from the U16 squad (15 years, 179 cm, 70 kg). We detected statistically significantly elevated peak pressures on the lateral aspects of the nonpreferred foot compared with the preferred foot in the U16 and U17 players, corresponding to a relative increase by 29% (p= 0.044) in the lateral midfoot, a relative increase by 24% (p= 0.031) in MT heads 4–5 in the U16 players and a difference of 18% (p= 0.049) in the lateral midfoot in the U17 players. In contrast, the U21 and adult professional players displayed symmetric plantar pressure distributions in all foot regions. CONCLUSIONS: In contrast to adult elite soccer players, adolescents demonstrate asymmetric foot loading patterns with increased peak loads in the lateral aspects of the nonpreferred foot. Our results may provide some explanation for MT V stress fractures that occur in elite adolescents.

Elevated Circulating Levels of Carnal ENST00000550337.1 Are Associated with Polycystic Ovary Syndrome in Chinese Women

2021 ◽  
pp. 1-7
Author(s):  
Yujuan Qi ◽  
Qianqian Yin ◽  
Juan Gu ◽  
Ying Liu ◽  
Qingqing Sun ◽  
...  
Keyword(s):  
Polycystic Ovary Syndrome ◽  
Peripheral Blood ◽  
Noncoding Rna ◽  
Chinese Women ◽  
Polycystic Ovary ◽  
Threshold Value ◽  
Expression Level ◽  
Ovary Syndrome ◽  
Blood Leukocytes ◽  
Cross Sectional

Objectives: Polycystic ovary syndrome (PCOS) is a common endocrine and metabolic disease. Some studies reported that the development of PCOS may be closely related to insulin resistance (IR). Interestingly, the long noncoding RNA (lncRNA) ENST00000550337.1 in peripheral blood is mainly involved in glucose metabolism. Therefore, the purpose of our study was to explore the relationship between lncRNA ENST00000550337.1 level and PCOS patients. Materials and Methods: Seventy-five PCOS patients and 72 healthy controls were enrolled in this study. We used qRT-PCR to detect the expression level of lncRNA ENST00000550337.1 in peripheral blood leukocytes from patients with PCOS. We also investigated potential relationships between lncRNA ENST00000550337.1 and the endocrine parameters in PCOS. Results: We observed that the expression of lncRNA ENST00000550337.1 in PCOS patients was significantly higher than that in the control subjects and positively correlated with PCOS occurrence, waist circumference, waist-hip ratio, IR, fasting insulin levels, and blood glucose. The expression of lnc RNA ENST00000550337.1 was positively correlated with PCOS (p = 0.003). There were independent correlations between IR and expression of lncRNA ENST00000550337.1 in patients with PCOS. Patients with elevated lncRNA ENST00000550337.1 expression had significantly increased PCOS risk after adjusting for age and BMI. LncRNA ENST00000550337.1 expression level provided a sensitivity of 81.3% and a specificity of 78.1% with a threshold value of 6.4648 for the prediction of PCOS. The area under the ROC was 0.813. Limitations: There are some limitations to this study. First, the sample size was limited and the causal relationship between lncRNA ENST00000550337.1 and PCOS was not investigated due to the cross-sectional study design. Second, HOMA-IR does not fully accurately reflect the IR of patients. Conclusions: The present study indicated that lnc RNA ENST00000550337.1 was related to PCOS occurrence, and elevated levels may be a risk factor for PCOS women. In addition, lncRNA ENST00000550337.1 might promote PCOS development partially by increasing IR and can be used as a potential molecular marker in patients with PCOS.

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