Double Frustum Research Articles

Calculation method for the ultimate bearing capacity of pressure-cast-in-situ pile with spray-expanded frustum

In this paper, the new type of Pressure-cast-in-situ pile with spray-expanded frustum (PPSF) developed by the authors is composed of pile body, ribbed plate, and expanded body with double frustum. The PPSF has the advantages of high bearing capacity, small settlement, high construction speed, and significant economic and environmental benefits. To evaluate the ultimate bearing capacity of PPSF, a calculation method is proposed considering the special shape of PPSF. The ultimate bearing capacity of PPSF is considered as the sum of three parts, e.g., the ultimate bearing capacity of expanded body with double frustum, the ultimate skin friction of pile body, and the ultimate end resistance of pile base. The failure mode of the soil around the expanded body with double frustum is described based on the Meyerhof’s bearing capacity theory. The calculation formula for the ultimate bearing capacity of the expanded body with double frustum is established using the sliding block balance method. The rationality of the calculation method is verified by three cases.

Effects of handle shape and texture on the hand-powered tools performance – A review

The performance of hand-powered tools, axil force, total/individual finger force, and subjective discomfort was examined in this study about the handle shape, including its lateral and longitudinal cross-sections, material surface (plastic and rubber), and workpiece orientation (horizontal and vertical). The functioning of hand-powered tools, the force transferred by the tool, and the involvements made by each finger to the overall distribution of grip force, on the other hand, are all impacted by design factors. In the case of a screwdriver, our current study found that cylindrical and reversed double frustum lateral handles, compared to triangular longitudinal cross-sectional handles, double frustum, and cone handles, were less uncomfortable. The newly created ergonomic hand tools for weaving were determined to be usable and acceptable by carpet weavers. In the case of Flat Files, our study finds that the files with handles bent between 50 and 70 degrees demonstrate their superiority.

All-Fiber Near-Field Optical Tweezer: Reducing Thermal Disturbance

Trapping nanoscale particles in a stable and non-destructive way is of great importance to life sciences. Near-field optical tweezers are a common way to trap nanoparticles. Here we propose and demonstrate an all-fiber near-field optical tweezer for trapping nanoparticles using a laser beam that has been totally reflected three times on a fiber tip with a double frustum structure. The light totally internally reflects on the optical fiber end-face and generates an evanescent field that traps the nanoparticles in water. Simulated results show that the evanescent field with high gradient distribution generating on the optical fiber end face leads to an insignificant temperature rise (0.0765 K). The experimental results demonstrate that all-fiber near-field optical tweezer allows us to trap fluorescent particles as small as 100 nanometers in diameter. The max temperature rise is 0.091 K. Compared with the plasmonic optical tweezers, the all-fiber optical tweezer reduces the thermal effect. The proposed all-fiber near-field optical tweezer plays an essential role in nanoscale optical trapping.

Pressure-Cast-In-Situ Pile with Spray-Expanded Frustum: Construction Equipment and Process

AbstractTo make full use of skin friction of soils around pile, this paper presents a novel pile composed of ribbed plates, an expanded body with double frustum, and a pile body, named as the press...

The Implementation of Stereoscopic 3-D Image by Using the Off-Axis Asymmetric Double Frustum

The Implementation of Stereoscopic 3-D Image by Using the Off-Axis Asymmetric Double Frustum

Improving the Accuracy of Parts Manufactured by Single Point Incremental Forming

The aim of this paper is to enrich the knowledge related to the single point incremental forming (SPIF) process by evaluating the efficiency of two optimization methods - the response surface method and the neural network method - to improve the accuracy of manufactured parts by prescribing a proper combination of the process parameters. The analysis is performed for a double frustum of pyramid made by stainless steel. It was found a good ability of prediction of both methods, demonstrating their suitability for physical implementation in solving problems associated to the SPIF process.

The Effect of Residual Stresses on the Accuracy of Parts Processed by SPIF

The aim of the present work was to investigate the residual stresses distribution within parts processed by single point incremental forming (SPIF) as a function of the working parameters and to determine its influence on the parts accuracy. The study was performed for a double frustum of pyramid made by 304 stainless steel. An experimental analysis was first conducted by using the strain-rosette method. Since the method allowed determining the residual stresses only locally, a numerical model was then elaborated to inspect the distribution of residual stresses throughout the whole part. It was found that a favorable state of residual stresses and implicitly a good accuracy of parts can be obtained when small values of tool diameter and tool vertical steps, respectively high values of feed rate and spindle speed, are used.

Simulated performance of a single pixel PIN spectrometer SCXM equipped with a concentrator optics in Solar coronal X-ray observations

In this paper we present simulated solar coronal X-ray observations to verify the sensitivity of a new hypothetical instrument design. These simulations are folded through this X-ray spectrometer having a moderate size circular field of view ( FoV) of 1.6°. This SCXM (Solar Coronal X-ray Mapper) is designed to compose of a single pixel silicon PIN detector equipped with a single reflection double frustum X-ray optics. A moderate FoV would enable a morphological study of the expanded X-ray emission from the solar corona during a high activity of the Sun. The main scientific task of SCXM would be the mapping of the coronal X-ray emission, i.e. to resolve the radial distribution of the X-ray surface brightness around the Sun. These kinds of off-limb observations would help to interpret the coronal plasma diagnostics as a function of the elongation angle. Direct solar full disc observations could be also performed with SCXM. In this work we have applied real solar coronal X-ray data obtained by the SMART-1 XSM (X-ray Solar Monitor) [3] to simulate on-solar observations at different flux levels to derive full disc sensitivity and performance of SCXM. A challenging attempt for SCXM would also be to distinguish the X-ray spectrum of the decaying axions around the Sun. These axions are assumed to be created as side products of fusion reactions in the core of the Sun. These axions are predicted to be gravitationally trapped to orbit the Sun forming a halo-like X-ray emitting object. No signature of an axion X-ray emission around the Sun has been observed to this day. This simple X-ray spectrometer with an optical concentrator would be an inexpensive instrument with low mass and telemetry budgets compared with more accurate X-ray instruments of imaging capability. Hence SCXM would be an advanced choice as an auxiliary instrument for solar coronal X-ray observations.

Research on the Blank Used in Integral Forming of a Lager Head with Supporting Table

Three-dimension rigid-plastic finite element software, DEFORM-3D, was used to simulate the integral forming processing of a lager thick-wall semi-sphere head with supporting tables. Influencing factors of integral forming, such as initial blank shape, radius of corner at the bottom of the protrusions and the preforming mode etc, were researched quantitatively. A double layer frustum cone blank was determined, which can reduce the variable amplitude of the wall thickness and cause a uniform wall thickness distribution. When radius of corner at the bottom of the protrusions of the machined blank was in 100~130mm, no crack occurred at the bottom of the any supporting tables and a rational size can be obtained after forming. Using mode C (two banding protrusions) to forging the blank for machining can prevent the center metal from thinning and reduce additional tensile stress. Based on the simulation research, the 1:3 scale experiment was done in 31.5MN hydraulic press and the test piece was measured. The result shows that the error between simulation data and test data is less than 5%, which verified the feasibility of integral forming and provided an important reference for virtual production.

Evaluation of handle design characteristics in a maximum screwdriving torque task

The purpose of this study was to evaluate the effects of screwdriver handle shape, surface material and workpiece orientation on torque performance, finger force distribution and muscle activity in a maximum screwdriving torque task. Twelve male subjects performed maximum screw-tightening exertions using screwdriver handles with three longitudinal shapes (circular, hexagonal and triangular), four lateral shapes (cylindrical, double frustum, cone and reversed double frustum) and two surfaces (rubber and plastic). The average finger force contributions to the total hand force were 28.1%, 39.3%, 26.5% and 6.2%, in order from index to little fingers; the average phalangeal segment force contributions were 47.3%, 14.0%, 20.5% and 18.1% for distal, middle, proximal and metacarpal phalanges, respectively. The plastic surface handles were associated with 15% less torque output (4.86 Nm) than the rubber coated handles (5.73 Nm). In general, the vertical workpiece orientation was associated with higher torque output (5.9 Nm) than the horizontal orientation (4.69 Nm). Analysis of handle shapes indicates that screwdrivers designed with a circular or hexagonal cross-sectional shape result in greater torque outputs (5.49 Nm, 5.57 Nm), with less total finger force (95 N, 105 N). In terms of lateral shape, reversed double frustum handles were associated with less torque output (5.23 Nm) than the double frustum (5.44 Nm) and cone (5.37 Nm) handles. Screwdriver handles designed with combinations of circular or hexagonal cross-sectional shapes with double frustum and cone lateral shapes were optimal in this study.

Evaluation of handle shapes for screwdriving

This study investigated the effects of screwdriver handle shape, surface, and workpiece orientation on subjective discomfort, number of screw-tightening rotations, screw-insertion time, axial screwdriving force, and finger contact forces in a screwdriving task. Handles with three longitudinal cross-sectional shapes (circular, hexagonal, triangular), four lateral shapes (cylindrical, double frustum, reversed double frustum, cone), and two surface materials (plastic, rubber coated) were tested. Individual phalangeal segment force distributions indicated how fingers and phalangeal segments were involved in the creation of total finger force (15.0%, 34.6%, 34.5%, and 15.9% for the index, middle, ring, and little fingers; and 45.7%, 22.4%, 12.9%, and 19.0% for the distal, middle, proximal, and metacarpal phalanges, respectively). From this finding, the index and little fingers appeared to contribute mainly in the guiding and balancing of the screwdriver handles, whereas middle and ring fingers played a more prominent role in gripping and turning. Participants preferred circular and hexagonal longitudinal-shaped and double frustum and cone lateral-shaped handles over the triangular longitudinal-shaped handles, and cylindrical and reversed double frustum lateral-shaped handles. Circular, cylindrical, and double frustum handles exhibited the least total finger force associated with screw insertion. In terms of combinations of longitudinal and lateral shapes, circular with double frustum handles were associated with less discomfort and total finger force.

Evaluation of Hook Handles in a Pulling Task

To evaluate the effect of handle design characteristics on subjective ratings and pulling forces, meat-hook handles with various handle shapes, sizes, and hook positions were tested in a pulling task. Finger and phalange force data measured by force sensitive resistors and subjective ratings of discomfort were also evaluated. Generally subjects preferred 37-mm double frustum, 30-mm oval handles followed by 30-mm double frustum handles, 37-mm oval, and 45-mm double frustum handles. In the analyses of total pulling force, 37- and 45-mm double frustum handles showed less required pulling force than the others. The averages of finger force contributions to the total pulling force were 27.2, 28.1, 23.9, and 20.8% in order from index to little fingers. The average of phalange force contributions were 28.8, 33.6, and 37.6% for the distal, middle, and proximal phalanges, respectively. The findings illustrate that the pulling finger forces and subjective discomfort ratings were related to the handle shape as well as handle size.

Evaluation of handles in a maximum gripping task

Various hook handles were tested to evaluate the effect of handle design characteristics on subjective discomfort ratings and phalange forces in a maximum gripping task. A force glove system with 12 thin force sensitive resistor (FSR) sensors was used to measure phalange forces on the hook handles. Thirty subjects (15 males and 15 females) were tested, and generally subjects preferred 30 or 37 mm (the latter for large handed males) double frustrum handles followed by 30 mm oval handles, whereas overall they showed less preference for 37 mm oval handles and 45 mm double frustrum handles. The phalange force was more related to handle shape than to handle size in this study, i.e. the individual phalange forces on oval handles were about 8% higher than those on double frustum handles. The force distributions in the maximum gripping task showed significant differences in finger and phalange forces, in the order of middle, index, ring, and little fingers and distal, middle, and proximal phalanges from the highest to the lowest forces. The findings of this study may provide guidelines for designing double frustum handles for satisfying user's preference and oval handles for obtaining high phalange forces in a maximum gripping task.

Evaluation of meat-hook handle shapes

Seven meat hooks including two current designs and five new designs with flat-rectangular, frustum, double frustum, and cylindrical shapes were evaluated. A two-phase study was conducted. In the first experiment, maximum pulling forces were measured by load cell to evaluate the effects of handle shapes on subjective discomfort, maximum pulling force, and muscle activity. Two pulling forces, 15 and 30 kg, were employed to a pulley mechanism to simulate pulling a beef carcass horizontally in the second experiment. FSR (force sensitive resistor) glove was used to measure the pulling forces on the meat hooks. The glove has 12 sensors that result in placement on the pulpy regions of each phalange. In addition, a biomechanical hand model was developed and applied to predict tendon forces. Double frustum shaped handles produced significantly larger maximum pulling forces and best force efficiency when normalizing forces with EMG. In terms of external forces as measured by the FSRs, the averages of finger force contributions to the total finger force were 27%, 32%, 32%, and 10% in order from index finger to little finger. The averages of phalange force contributions to the total finger force were 20.9%, 33.7% and 45.4% for the distal, middle and proximal phalanges, respectively. A Chi-square analysis indicated that the phalange force distribution for double frustum handles deviated least from the average contributions for all hooks. Double frustum handles showed the least predicted tendon forces and normalized tendon forces per unit external force. The optimality of double frustum shaped handles was also supported by the lowest discomfort ratings. Therefore, based on both empirical physiological measurements and theoretical biomechanical calculations, a double frustum handle is most efficient for pulling task, producing the least amount of tendon forces. Relevance to Industry Results obtained from this handle study will help to reduce the ergonomic risk factors of finger/hand disorders for meat hook workers who use the meat hooks with a long daily duration and high force.

Determination of Optimal Handle Sizes by use of Normalized Hand Sizes in a Pulling Task

Two handle shapes (double frustum and oval) with different sizes, resulting in a total of 10 handles were tested to determine optimal handle sizes in a pulling task. Force data were collected by force sensitive resistors (FSR), which were placed on the palmar surface of the fingers. Subjective ratings of discomfort were also recorded for each handle. The results of subjective ratings showed that medium sized-handles were described as being more comfortable than the other sizes, and double frustum handles required less finger forces than oval handles. ‘Normalized Hand Size (NHS)’, which is the ratio of handle circumference to user's hand length was applied to predict the optimum handle size for the subjective ratings as well as finger forces in a pulling task according to the user's hand size. in oval handles, generally medium handles showed higher preference and required less finger forces than large handles. in case of the double frustum handles, the 60.9% NHS was the best ratio for the least subjective discomfort ratings and the 58.1% NHS was recommendable for the least finger force requiring in a pulling task. Based on the results of NHS study, 34.4∼38.1 mm and 31.4∼35.0 mm were recommended for middle hand size groups of male and female, respectively. The optimum handle sizes for the males were about 8.1∼8.7% larger than that of the female.

Evaluation of the Finger and Phalange Froce Distributions in Pulling Task

The pulling finger/phalange force distributions were investigated with various handles. Generally, oval handles required higher forces than double frustum handles in pulling task. The finger force distributions of the pulling task were similar to those of the gripping task. Middle (28%) and index (27.2%) were the strongest and little (20.8%) showed the lowest, followed by ring (23.9%). However, the phalange force distributions of the pulling task were different from the gripping task. Proximal (37.6%) produced the largest and middle (33.6%) also exerted more forces than distal (28.8%) phalanges. As the handle size increased, the forces of index and middle fingers showed increasing trends while ring and little fingers had decreasing trends. The phalange force was being moved more on distal phalanges than on proximal and middle phalanges. The understanding of force distributions may help to develop biomechanical finger models and to design hand tools for reducing related hand injuries.

A novel microelectromechanical system (MEMS) design for an underwater acoustic field sensor

A concept for underwater acoustic imaging exploits current technology for constructing MEMS devices from silicon wafers. Anisotropic etching creates frustum-shaped (pyramids with tops cut off) holes in a wafer chip; the bonding of two such chips creates double frustum-shaped holes, each analogous to an hour glass. The front side of each hole is a tapered duct with a baffled open end. The acoustic disturbance generated by an incident plane wave magnifies as the flow converges toward the waist. The back half of the double frustum is covered by a third silicon layer and acts as a Helmholtz resonator, the waist being the neck. The manufacturing process places a thin membrane across the waist which oscillates sychronously with the acoustically induced fluid motion. An appropriate design can achieve fluid velocities at the neck much larger than what would be associated with the incident acoustic wave in free space, and exploratory experiments confirm this. The oscillating membrane is sensed by an optical system, and theoretical extrapolation of the measured displacement amplitude yields a measurement of the amplitude of the incident acoustic wave. [Work supported by Indian Head Divison, Naval Surface Warfare Center, as part of the DARPA Sonoelectronics Program.]