Circular Groove Research Articles

The Analysis of Post-Mount in W-Band Circular Groove Guide

Finite-difference time-domain (FDTD) method is used to calculate the driving-point impedance of the circular groove guide diode mount. A simple way is proposed to approximate the curvilinear metal boundary of circular groove guide. Discrete equations are obtained from the Ampere's law and Faraday's law. Perfectly matched layer (PML) is applied on the open boundary of circular groove guide. At last program is made to obtain the field components. The driving-point impedance can be achieved from the ratio of the Fourier transform of the voltage and the Fourier transform of the current. The cutoff frequency and field pattern of the dominant mode are also obtained with well agreement with the theoretical results, this verifies the validity of the FDTD program.

Rectangular-to-circular groove waveguide junction

Mode matching method is used to analyze the scattering characteristics of the rectangular-to-circular groove waveguide junction. Firstly, the scattering matrix equation is obtained by matching the electromagnetic fields at the boundary of the junction. The scattering coefficients can be obtained from the equation. Secondly the scattering characteristics of the iris with rectangular window positioned in circular groove waveguide are briefly analyzed. Thirdly, the convergent problem is discussed and the numerical results are given. At last experiment is made and good agreement is found between the calculated results and the measured results.

Using Guided Balls to Auto-Balance Rotors

By using balancing balls constrained to move in a circular groove filled with oil, the vibration of rotating machinery can, under certain circumstances, be reduced. This paper shows that the damping from the oil reduces the instability region, i.e., the conditions when the balancing balls don’t find their equilibrium positions. However, the instability region seems to increase with increasing number of balancing balls. The critical ball damping ratio is highest just above the natural frequency and then rapidly decreases. Consequently, since the region between instability and critical damping is quite small, the ball damping should be made as small as possible without getting too close to the instability threshold. Bearing damping has a large effect on the instability region. High bearing damping will suppress the instability. The time it takes to reach the asymptotically stable position seems to increase with increasing number of balls. Keeping this time low is one of the most important things when designing a balancing ring.

Morphological characteristics of the tongue and its papillae in the donkey (Equus asinus): a light and scanning electron microscopical study

The morphology of the donkey tongue and its papillae were investigated by macroscopy and by light and scanning electron microscopy in ten adult animals (six males and four females). The spatula-shaped tongues measured about 28 cm in length, 4.5 cm in breadth and 3.5 cm in thickness. Samples from different areas of four tongues were grossly examined and pieces were processed for light and scanning electron microscopy. Filiform papillae were distributed mainly on the dorsum of the tongue, being thin and relatively short at the apex, conical and scaly in the main part (triangular zone) of the body, and thin and longer at the caudal part of the body. Few of them were found on the lateral surfaces. Fungiform papillae appeared scattered mainly on the lateral surfaces. They were mostly rounded (about 1.0 mm in diameter), but lobulated forms were also observed. Filiform and fungiform papillae were both completely devoid of taste buds, indicating a more mechanical function. The vallate papillae were 2-3 in number, located at the most caudal part of the body. They were three to four times as large as the fungiform papillae (about 5.6 mm in diameter) each with a wide circular groove around the central bulbous projection. Secondary grooves originating from the primary one were also demonstrated. The vallate papillae contained many taste buds with taste pores opening deeply into the papillary groove. Fine filiform papillae were demonstrated on the bulb-like part of the vallate papillae. The donkey tongue had sinister and dexter well-developed sets of foliate papillae close to the basis of the palatoglossal arch. They were arranged in the form of numerous leaves separated by deep, variably wide grooves and contained a very large number of taste buds. It is believed that the existence of well developed foliate papillae in donkey may substitute the comparatively few vallate papillae in this species.

Bone ingrowth on a smooth-surfaced hydroxyapatite-coated acetabular cup.

We studied 29 retrieved smooth-surfaced hydroxyapatite (HA)-coated acetabular cups that had been in situ for an average of 54.9 months. The outer surface of all cups carried two circular grooves dividing the smooth surface. The extent of bony in-growth and hydroxyapatite absorption was calculated using a computer imaging system (analySIS-pro 3.0, Soft Imaging System GmbH, Germany). Absorption of HA was seen in all 29 cups. The extent of absorption was, on average, 60.5%. Twenty-five cups showed bony in-growth covering an average of 13.8% of the cup surface. Thirteen cups showed bony in-growth on the smooth surface as well as the circular grooves. On 11 cups, the bony in-growth was confined to the grooves. We found that bony in-growth on the smooth-surfaced HA-coated acetabular cup was minimal. It occurred along the two circular grooves rather than on the smooth surfaces. We conclude that a macro-structure surface enhancing bony in-growth is necessary for the long-term survival of the studied cup.

High temperature oxidation of Si(100) by neutral oxygen cluster beam: Coexistence of active and passive oxidation areas

We report the study of Si(100) oxidation by oxygen clusters with an average size of 2000 molecules at substrate temperatures ranging from 850 to 1100 °C. It has been found that at T<1000 °C two areas corresponding to passive and active oxidation of silicon coexist within the same impact spot on the surface. In the central part of the impact spot, no surface etching occurs due to the formation of a protective oxide layer. In the area surrounding the central part, a circular groove with a steep inner and slightly sloping outer walls is formed as a result of surface etching via the reaction 2Si+O2→2SiO(gas). The reactive sticking coefficient of oxygen obtained from the etch rate in active oxidation area is significantly higher than that for oxidation by molecular oxygen. The coexistence of the two areas is attributed to a quasi-Gaussian flux density distribution in the beam cross section. The observed abrupt drop of the etch rate at the inner wall of the groove marks the transition from active to passive oxidation. Silicon oxidation by an oxygen cluster beam shows specific features that have not been observed in previous works with molecular oxygen. The critical flux density corresponding to the transition does not, for instance show an Arrhenius behavior. Besides, this study shows the crucial role of the beam spatial parameters when supersonic sources are used to study surface reactions.

Groove design of vacuum chucks for hot embossing lithography

A preliminary study of the suitability of vacuum chucks for fixing of stamp and sample in a hot embossing lithography process was performed. Four inch test chucks were designed, featuring circular grooves and isolated holes of 0.7 to 2 mm size. The effect of these grooves was tested by imprint into PMMA with an unpatterned stamp. The processed samples showed a polymer thickness variation correlated with the groove locations, which could be measured with a profilometer. The thickness variations found were of different type when polymers of different molecular weight were used. Under realistic embossing conditions, values of up to 70 nm were measured. From the experiments, an allowable groove width of <1 mm could be deduced.

Minimum-Risk Bedding for Flexible Drain Pipes

The soil bedding for nonpressurized buried flexible pipes is critical for minimum-risk performance. Lack of adequate bedding reduces the strength of the pipes by a factor of 2 or more. To compensate, pipes must have high strength, at increased cost, in order to avoid the risk of failure. Structural performance and performance limits are compared for plastic drainpipes with a variety of beddings. Compared to a flat bedding, the risk of failure is greatly reduced by shaping the bedding. Shaped beddings perform essentially as well as full-contact embedment with select granular soil. Tests and analyses show that a 90° V-groove bedding that supports and aligns the pipe performs nearly as well as a 180° form-fit circular groove or a full-contact embedment of select soil. Comparison of beddings is important in the design and installation of drainpipes in order to assure minimum risk of failure.

Momentum exchange alteration in projectile/target impact

This research represents an effort to alter the exchange of momentum per unit area when a projectile centrally impacts a circular 6061-T6 aluminum target, 6.35 mm thick, at normal incidence. This is achieved by cutting a circular groove of appropriate depth and diameter in the back of the target. This procedure effectively reduces the strength of the plate at the groove so that under certain conditions the part of the target inscribed by the groove is ejected as a plug. Two independent sequences of experiments were executed. Initially, a number of tests were conducted to establish the ballistic limit, v 50, for ungrooved plates and to ascertain possible variations in target response mechanisms when 40° triangular grooves with a constant diameter of 25.4 mm and depths ranging from 0.79 to 3.175 mm were cut into the back of the targets. This preliminary series established the behavior pattern of the momentum transfer to the target. A subsequent series of tests utilized a standard 60° triangular groove, a constant groove depth of 4.76 mm and varied groove diameters ranging from 19.1 to 44.4 mm. Initial impact velocities ranged up to 950 m/s, mostly with the pointed end making initial contact. Several regimes of projectile/target behavior were observed: (1) Rebound without plugging, (2) Plugging without perforation, (3) Perforation of a subsequently dislodged plug, and (4) Perforation without plugging. These regimes are defined by a relation between plug diameter and a range of initial striker speed. The momentum transferred to the targets was also determined.

Study on ceramic/polymer composite fabricated by laser cutting

Piezoelectric ceramic/polymer composites are important smart materials that have found many sensor and mechatronic device applications. In this work, piezoelectric lead zirconate titanate (PZT) ceramic was cut using a high power laser to obtain very fine scale patterns. The advantage of using laser cutting is that new and innovative pattern design can be implemented. To illustrate this, fine concentric circular grooves were cut in a 10 mm diameter PZT disc and then the grooves were filled with epoxy to form a ceramic/polymer 2–2 composite. Also a 1–3 composite consisting of PZT rods imbedded in a polymer matrix was fabricated. The electromechanical properties of these composites were measured and reported.

An improvement on analytic accuracy of circular groove guide

In this paper, an Nth order approximate eigenequation of circular groove guide is presented. Using the sixth order approximate results, some propagation properties of the TE/sub 11/ mode of circular groove guide are recalculated. The results are more accurate than before and in good agreement with the measurements.

Bone Ongrowth of Hydroxyapatite-Coated ABG Acetabular Cups

Purpose : To evaluate the efficacy of the smooth surface hydroxyapatite (HA)-coated acetabular cup in total hip arthroplasty. Materials and Methods : From March 1992 to June 1998, 289 smooth surface HA coated acetabular cups were implanted. This study included 29 retrieved cups that had been in situ for an average of 54.9 months. The three dimensional acetabular cups were converted into two dimensional figures using a digital camera, and the ratio of bone ongrowth and HA absorption were calculated using a computer imaging analysis system (analySIS-pro 3.0, Soft Imaging System GmbH, Germany). The central hole and the peripheral 12 holes were excluded from total surface area of the cup, which was divided into 3 surfaces by 2 circular grooves. Results : Bone ingrowth was noted in 26 of the 29 cases; in 11 cases (37.9%) on the central surface, 12 cases (41.3%) on the middle surface and 8 cases (27.5%) on the peripheral surface. Bone ongrowth was noted in 22 cases (75.8%) on the medial groove and in 21 cases (72.4%) on the lateral groove. The average rate of bone ongrowth was 13.8 percent. HA absorption was noted in all cases and averaged 60.5 percent. Conclusion : Bone ongrowth on the smooth surface HA-coated acetabular cup was very scant. Bone ongrowth was seen more on the grooves than on the surfaces. We believe that a rough surface would enhance bone growth on HA-coated acetabular cup.

Analysis of Aperture Field of Circular Groove Guide Horn Antenna by Using FD-TD Method

This paper presents an instance of using FD-TD method to analyze the aperture field of circular groove guide horn antenna. This process is one part of a hybrid method to solve the radiation field of aperture antenna. To verify the calculated aperture field the radiation pattern is computed from it and compared with the measured one. Good agreement is reached.

The Further Study of Corrugated Circular Groove Waveguides by Using Method of Space Harmonics

By using method of space harmonics in the interior and higher order modes in the slot region of the corrugated circular groove waveguide, The dispersive equation of this waveguide is derived.

高炭素鋼溶接金属の高温割れにおよぼす炭素含有量および包晶反応の影響

The hot cracking sensitivity was examined on a series of weld metals of which the carbon content was varied systematically from 0.07 to 0.95%. The cracking sensitivity of weld metal was compared by the cracking test with a self-restraint type specimen. A weld metal was deposited in a circular groove of 80mm in diameter by MAG welding. Weld metals of various carbon contents were obtained by combining each of twelve electrode wires (0.004 to 1.0%C) and three base metals (0.23 to 0.77%C). The cracking sensitivity of each weld metal was expressed by the total length of cracking. The cracking sensitivity increases abruptly when the carbon content of weld metal exceeds 0.20%. It increases to the maximum at 0.40%C and then reduces to the minimum at 0.65%C. This result quite differs from the generally accepted idea that the more is the carbon content of weld metal, the greater becomes its cracking sensitivity. This result was referred to the phase diagram of Fe-C-0.5%Si system in which the peritectic reaction; delta-ferrite+liquid→austenite takes place. For the alloys of 0.20 to 0.65%C, the liquid remains after the reaction. Phosphorus once dissolved in delta-ferrite will be rejected into the remaining liquid. It lowers the final freezing temperature of remaining liquid locating between the dendrites and increases the cracking sensitivity of weld metal. This action is likely to arise most intensively in the alloy of 0.4%C and least in that of 0.65%. Sulfur seems to assist the harmful effect of phosphorus.

Circular Groove Guide Coupled with High-Q Cavity

The structure of circular groove guide coupled with high-Q cavity is studied. As a new type of millimeter wave component, it can be used for wavemeter and highly stabilized circular groove guide oscillator. The design and analysis of the novel structure are given in this paper.

Enhanced light transmission through a single subwavelength aperture

The optical transmission through a subwavelength aperture in a metal film is strongly enhanced when the incident light is resonant with surface plasmons at the corrugated metal surface surrounding the aperture. Conversely, the aperture acts as a novel probe of the surface plasmons, yielding useful insights for optimizing the transmission enhancement. For the optimal corrugation geometry, a set of concentric circular grooves, three times more light is transmitted through the central subwavelength aperture than directly impinges upon it. This effect is useful in the fabrication of near-field optical devices with extremely high optical throughput.

Design of a Rectangular to Circular Groove Waveguide Transition by Finite Element Method

A rectangular to circular groove waveguide transition is described in millimeter-wave band. The transition maintains a constant cutoff wavelength. Using the Finite Element Method, the size of the variable cross-section throughout the transition are calculated and the transition is designed.

Attenuation Characteristics of Corrugated Circular Groove Waveguide

When neglecting space harmonics and higher-order slot modes, the attenuation characteristic of corrugated circular groove waveguide has been investigated. It is shown that under certain conditions, the attenuation coefficient of HE11 mode will be lower than that of dominant TE(1)11 mode of circular groove waveguide with same radius.

The Characteristic Equation of Corrugated Circular Groove Guide

Using the mode matching technique and neglecting the space harmonics, the characteristic equation of corrugated circular groove guide is given.