Strip Size Research Articles

Diffraction of waveguide waves by a finite system of strips in a layered dielectric

Microwave engineering uses leaky-wave antennas, which are planar dielectric waveguides with metal strips deposited on their surface. The analysis of such antennas in the literature known to us [i, 2] is made in the approximation of an infinite periodic grating without variation of the field along the strips; this can result in a large error in the calculation of real antennas with a limited number of strips and strip sizes. Nonperiodic gratings, which are the basis for the fabrication of antennas with enhanced characteristics, cannot be studied in this approximation [3]. In our study we obtained the solution of the boundary problem for the diffraction of waveguide waves by a finite number of metal ribbons without any limitation on their size. The solution also makes it possible to study the properties of higher leaky waves of microstrip lines and to make an exact calculation of waveguide filters formed by metal strips deposited on a dielectric substrate in the E plane of a rectangular waveguide. Such filters have found application in the millimeter range [4, 5]. In contrast to those studies, we take the effect of the dielectric substrate into account. Let us consider a two-dimensional layered structure (the boundaries of the layers are parallel to the xz plane), in which N infinitesimally thin ideal conducting strips lie on one boundary (Fig. I). Boundary conditions of the "electric wall" or "magnetic wall" type are satisfied on the horizontal screens. One or both screens may be absent, in which even the conditions for emission are assumed to be satisfied.

An Experimental Study of a Plasto-Hydrodynamic Strip Drawing Process

Experimental results are presented for a new dieless strip drawing process in which conventional wedge-shaped dies have been replaced by a reduction unit having a stepped rectangular cavity. The smallest cavity dimensions are larger than those of the incoming strip, thus eliminating the problem of die friction and consequential tool wear. In this novel process, the strip is passed through a chamber filled with polymer melt and then pulled through the reduction unit. The strip material is deformed due to the combined effects of shear drag and the hydrodynamic pressure generated by the converging flow of the polymer melt. Experiments were carried out in which the process parameters such as the unit geometry, speed and polymer melt temperature and hence viscosity were varied and the hydrodynamic pressure, reduction in strip size and drawing load were measured. Initial experiments were carried out by using copper strip and low-density polyethylene at two different melt temperatures. Results from experiments showed that a reduction in area of strip of more than 10 per cent could be achieved in a single pass. The Newtonian analysis presented by the authors in reference (9) is modified to incorporate the critical shear stress limit of the polymer melt and the non-linear strain-hardening property of the strip material.

On a diffusion model for sterile insect release

The sterile insect release method (SIRM) for pest control is modeled by a reaction-diffusion equation. Conditions on the strip size of the favorable environment and the initial population to avoid an outbreak state are obtained by using a combination of analytical and numerical techniques.

Minimum Cooking Time for Potato Strip Frying

ABSTRACTThe maximum force for shearing was used as texture parameter for raw and cooked potato strips. The force was satisfactorily correlated with the cook value C (equivalent cooking time at 100°C) showing complete cooking for C ≥ 300 sec. Thermal histories measured at the center of strips fried under different oil temperatures suggested the heat and mass transfer mechanisms involved in the frying process and allowed the calculation of the minimum frying time to assure cooking at the strip center. This time was independent of the oil temperature and slightly dependent on the strip size.

突き合せ溶接継手の曲げ疲労強度に及ぼす裏当金形状の影響

Since a fatigue crack of the butt welded joint with a backing strip initiates at the toe of root, fatigue strength of the joint may be strongly influenced by the form and size of the backing strip. Therefore, reversed bending tests were carried out to clarify the relation between stress concentration and fatigue strength of the butt welded joint with a backing strip, by varying the form. and size of the backing strip.In a notched specimen, when a non-propagating crack exists at the root of a notch whose radius is smaller than the root radius of a notch at the branch point (the critical point where a non-propagating crack appears), the fatigue limit of the notched specimen can be estimated from the maximum stress at the root of a notch with no crack developing, whose radius is equal to that at the branch point.As the butt welded joint with a backing strip can be considered as a kind of sharp notches, the fatigue limit of the joint is estimated in a similar manner as in the case of a sharp notch.The specimens used are the simulated specimens cut out from a SS41 plate.The main results obtained are as follows;(1) As the thickness of a backing strip or the root opening decreases, fatigue strength of the butt welded joint increases.(2) In the butt welded joint with a backing strip, the existence of reinforcement increases fatigue strength of the joint.(3) When the notch radius at the toe of root is smaller than the critical radius for the existence of a nonpropagating crack, the fatigue limits of the joint are almost the same under the condition of constant thickness of the specimen and backing strip.

The Susceptance of an Annular Metallic Strip in a Circular Waveguide with Incident TE/sub 01/ Mode

The principal aims of this paper are twofold: 1) to solve the problem of the scattering of a thin, perfectly conducting aonular strip suspended in a multimodal circular waveguide in which any number of TE/sub 0n/ modes can propagate, and with the aid of this result, 2) to give the susceptance of the thin annular strip in monomodal circular guide with an incident TE/sub 01/ mode. These are treated with a variational approach. Applying the appropriate Green's functions to the continuity equations for the transverse electric field yields a variational expansion for the scattering matrix elements. This is treated with a Rayleigh-Ritz procedure and matrix methods. Curves of normalized susceptance as a function of the free-space wavelength and the size of the annular metallic strip are shown. These results are in good agreement with experimental data. Tables of the scattering coefficients for a typical wavelength versus strip size are also included.

国産鉄粉より粉末圧延法で製造した薄板の顕微鏡組織

Using the powder rolling method, an attempt has been made to clarify the relationship between the microstructure and the physical and mechanical properties of sintered and cold-rolled strips made from three kinds of domestic iron powders. In the case of sintered strips, the voids in strips were decreased with the increase in powder rolling load and with the decrease in particle size, but the grain size of strips was scarcely affected. The properties of sintered strips were affected mainly by the voids in strips rather than the grain size. In the case of sintered strips, the voids were diminished and the grain size of strips became finer as the powder rolling load increases and the size of powder particles becomes smaller. With the increase in purity of powder, the microstructure of strips showed more distinct polygonal structure, corresponding to the increase in apparent density and elongation of strips. The grain size of sintered strips was finer than original particle size of powder and that of cold-rolled strips was much finer than that of sintered ones. These results suggest that the high purity iron strips containing small grains can be produced by the powder rolling method.

Development and Application of an Apparatus for Continuous Measurement of Muscle Extensibility and Elasticity Before and During Rigor Mortisa,a,b

SUMMARYAn apparatus was developed to study the extensibility and elasticity characteristics of muscle fibers before and during the onset of rigor mortis. A variable load (weight) was applied to a muscle specimen held in a chamber under controlled conditions maintained by a thermostatically regulated cartridge heater, cooling coil, and gas inlet. A solenoid cell, energized by a cyclic timer, was used to release and apply the load in a direction longitudinal to the vertically mounted specimen. A lever attached to the specimen‐loading, system transmitted the extensibility and elasticity of the specimen to the armature of a differential transformer. The output voltage, from the secondary transformer winding was directly proportional to displacement of the armature. This AC output signal was rectified and transferred to a DC recording microammeter. The time course of rigor mortis was not influenced by loading and unloading interval or size of muscle strip, and was found to be temperature‐dependent, being prolonged as temperature was decreased. The white fibers of the semitendinosus muscle were found to have a considerably longer delay phase than the red fibers. The relations between the time course of rigor mortis and the ultimate properties of the muscle were discussed.

Magnetic Field Measurement Using Ultrasonics

The detection and measurement of magnetic field intensity for purposes of field plotting and uniformity studies is a most important consideration in the field of magnetics. Field plotting and uniformity studies have been conducted on certain sizes of magnetic geometries with rotating coil instruments and Hall generators and quartz crystal magnetometer. The obvious limit of such devices is their minimum resolving power which can be defined in terms of sampling area and mimimum air gap. For the rotating coil instruments, the minimum air gap is 14 in. and the sampling area is roughly 1.2 × 10−2 sq in. Commercially available Hall generators which can be fitted into air gaps of approximately 0.011 in. have sampling areas in the order of 3.2 × 10−3 sq in. Hall generators with sampling areas in the order of 10−7 sq in. have been reported in the literature. Minimum thickness of this type device is presumably less than 0.01 in. The more recent work with the vibrating quartz crystal magnetometer has been used to measure flux density normal to the surface of permanent magnets. The sampling area of this type of equipment is 0.56 × 10−6 sq in. The minimum thickness of this equipment has not yet been reported in the literature. The flux-measuring equipment being described in this paper has a sampling area of approximately 6.25 × 10−6 sq in. and a senstivity of approximately 0.01 × 10−3 v/gauss. The probe consists of a single turn inductor of length 116 in. which vibrates ±0.00005 in. The inductor is fastened to a probe of 0.01 in. thickness and the 0.0001 in. motion is perpendicular to this 0.01 in. probe thickness. The physical geometry and size of this probe permits measurements in a variety of positions relative to the magnetic circuit. This type of probe is applicable for measuring flux density in air gaps as small as 0.017 in. The driving device for this equipment is a 60 Kcps magnetostrictive transducer. The complete probe consists of the transducer reactor, a coupling bar of nonmagnetic stainless steel and the thin strip of the nonmagnetic stainless to which the inductoris fastened. The geometry and size of this thin strip can be changed to accommodate variations in both inductor length and displacement.

Methods of reducing chromatic aberration in metal-plate microwave lenses

Microwave lenses of the waveguide type are subject to a pronounced degree of chromatic aberration because of the inherent dispersion of the waveguides. However, this aberration can be substantially eliminated over an appreciable bandwidth by making the lens of slot-loaded ridged waveguides with special properties. This type of lens design makes it possible to achieve additional benefits as well, such as improved scanning capability and elimination of discontinuities in the surfaces at the junction of adjacent "zones" or "steps." The ridged waveguides are periodically loaded by means of transverse slots in the ridges. The ridges may be relatively wide and hollow, or quite thin and solid. Additional desirable properties are obtainable by placing a relatively small strip of dielectric material above the ridge. Experimental data on the propagation characteristics of several of these structures and on the effect of varying such parameters as ridge height, slot width, slot depth, slot spacing, frequency, and size of dielectric strip are given. An analysis of the phase errors which result from changes in the operating frequency shows that the aberrations may conveniently be separated into one type in which the phase front from each zone of the lens is distorted, and a second independent type in which the desired phase relationship between the zones is destroyed. Methods of eliminating either or both of these types of aberration by suitable design of the ridged waveguides are described. In addition, it is shown how the ridged waveguides can conveniently be used to achieve "zoning" or "stepping" by changing the effective index of thereby eliminating discontinuities in the lens surfaces and avoiding the undesirable diffraction which would otherwise occur at the boundaries between adjacent zones. The superiority of this type of lens structure in wide-angle scanning applications is also discussed. Numerical examples which illustrate the advantages of the loaded ridged waveguide lens are included.