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Directional Systems is a signage supplier, providing quality signs to the banking, parking, hospital, education, airport and other commercial sectors. Our illuminated signs are available in direct-view LED or backlit LED. We also carry non-illuminated aluminum signs that include: clearance signs, directional post & panel signs, and building identification signs.
A directional antenna or beam antenna is an antenna which radiates or receives greater radio wave power in specific directions. Directional antennas can radiate radio waves in beams, when greater concentration of radiation in a certain direction is desired, or in receiving antennas receive radio waves from one specific direction only. This can increase the power transmitted to receivers in that direction, or reduce interference from unwanted sources. This contrasts with omnidirectional antennas such as dipole antennas which radiate radio waves over a wide angle, or receive from a wide angle.
The extent to which an antenna's angular distribution of radiated power, its radiation pattern, is concentrated in one direction is measured by a parameter called antenna gain. A high-gain antenna (HGA) is a directional antenna with a focused, narrow beam width, permitting more precise targeting of the radio signals. Most commonly referred to during space missions, these antennas are also in use all over Earth, most successfully in flat, open areas where there are no mountains to disrupt radiowaves. By contrast, a low-gain antenna (LGA) is an omnidirectional antenna with a broad radiowave beam width, that allows the signal to propagate reasonably well even in mountainous regions and is thus more reliable regardless of terrain. Low-gain antennas are often used in spacecraft as a backup to the high-gain antenna, which transmits a much narrower beam and is therefore susceptible to loss of signal.
All practical antennas are at least somewhat directional, although usually only the direction in the plane parallel to the earth is considered, and practical antennas can easily be omnidirectional in one plane. The most common types are the Yagi antenna, the log-periodic antenna, and the corner reflector antenna, which are frequently combined and commercially sold as residential TV antennas. Cellular repeaters often make use of external directional antennas to give a far greater signal than can be obtained on a standard cell phone. Satellite television receivers usually use parabolic antennas. For long and medium wavelength frequencies, tower arrays are used in most cases as directional antennas.
Directional Technologies is advancing the environmental and utility industries. Founded in 1992, Directional Technologies specializes in horizontal directional drilling (HDD) and implementing remediation technologies with horizontal wells. HDD is a steerable and trenchless method of installing utilities and horizontal wells. This established and proven method avoids costly trenching and site restoration; avoids disrupting businesses and operations; and, avoids impacts on pedestrians and vehicular traffic congestion.
As an environmental directional drilling company, we have installed thousands of horizontal wells beneath buildings, active facilities, railroads, highways, airports, wetlands as well as other sensitive areas and infrastructure. In many instances, horizontal remediation wells outperform their vertical counterparts and expedite site cleanup times.
This article targets you as a data modeler working with Power BI Desktop. It provides you with guidance on when to create bi-directional model relationships. A bi-directional relationship is one that filters in both directions.
Bi-directional relationships can deliver slicers that limit items to where data exists. (If you're familiar with Excel PivotTables and slicers, it's the default behavior when sourcing data from a Power BI dataset, or an Analysis Services model.) To help explain what it means, first consider the following model diagram.
A different scenario involving bi-directional relationships treats a fact-type table like a bridging table. This way, it supports analyzing dimension-type table data within the filter context of a different dimension-type table.
With over 30 years experience in the design and manufacturing of premium quality drilling motors, Mpact Downhole Motors is a leading supplier to the Domestic U.S. directional, horizontal, and vertical drilling markets.
With over 30 years of experience in the industry, MS Directional is ranked as a leading independent directional drilling services company with an established presence in most major producing onshore oil and gas basins in the United States.
As one of the most comprehensive oilfield service companies, our divisions provide expertise in directional planning, directional drilling, downhole performance motors, MWD, steering tools and downhole electric wireline.
Directional and informational signs are intended to guide motorists to various businesses, services or activities. Certain requirements must be met in order to legally erect a sign. The table below provides links to additional information for the various directional and informational signs.
Study eligibility criteria: Studies that reported time-motion analysis data on straight-line running, accelerations/decelerations, activity changes, jumping, cutting, or lateral movement over the course of an entire competition in a multi-directional sport (soccer, basketball, lacrosse, handball, field hockey, futsal, volleyball) were included.
Study appraisal and synthesis methods: Data was organized based on sport, age level, and sex and descriptive statistics of the frequency, intensity, time, and volume of the characteristics of running and multi-directional demands were extracted from each study.
Conclusions: Considerable variability exists in the demands of straight-line running and multi-directional demands across sports, competition levels, and sexes, indicating the need for sports medicine clinicians to design future rehabilitation programs with improved specificity (including the type of activity and dosage) to these demands.
Seattle changed the directional scheme for street names by Ordinance 89910 in 1961. Older documents, including modern indexes to them such as the Seattle Municipal Archives photograph index, often use the directional designations in effect at the time the documents were created. Use the maps on this page to translate this information to modern directional designations.
Cancer-associated fibroblasts (CAFs) are major components of the carcinoma microenvironment that promote tumor progression. However, the mechanisms by which CAFs regulate cancer cell migration are poorly understood. In this study, we show that fibronectin (Fn) assembled by CAFs mediates CAF-cancer cell association and directional migration. Compared with normal fibroblasts, CAFs produce an Fn-rich extracellular matrix with anisotropic fiber orientation, which guides the cancer cells to migrate directionally. CAFs align the Fn matrix by increasing nonmuscle myosin II- and platelet-derived growth factor receptor α-mediated contractility and traction forces, which are transduced to Fn through α5β1 integrin. We further show that prostate cancer cells use αv integrin to migrate efficiently and directionally on CAF-derived matrices. We demonstrate that aligned Fn is a prominent feature of invasion sites in human prostatic and pancreatic carcinoma samples. Collectively, we present a new mechanism by which CAFs organize the Fn matrix and promote directional cancer cell migration.
An antenna gives the wireless system three fundamental properties: gain, direction and polarization. Gain is a measure of increase in power. Gain is the amount of increase in energy that an antenna adds to a radio frequency (RF) signal. Direction is the shape of the transmission pattern. As the gain of a directional antenna increases, the angle of radiation usually decreases. This provides a greater coverage distance, but with a reduced coverage angle. The coverage area or radiation pattern is measured in degrees. These angles are measured in degrees and are called beamwidths.
Omnidirectional antennas have a similar radiation pattern. These antennas provide a 360 degree horizontal radiation pattern. These are used when coverage is required in all directions (horizontally) from the antenna with varying degrees of vertical coverage. Polarization is the physical orientation of the element on the antenna that actually emits the RF energy. An omnidirectional antenna, for example, is usually a vertical polarized antenna.
Directional antennas focus the RF energy in a particular direction. As the gain of a directional antenna increases, the coverage distance increases, but the effective coverage angle decreases. For directional antennas, the lobes are pushed in a certain direction and little energy is there on the back side of the antenna.
Omni antennas are very easy to install. Due to the 360 degrees horizontal pattern, it can even be mounted upside down from a ceiling in the indoor environment. Also, because of its shape it is very convenient to attach these antennas to the product. For example, you might see Rubber Duck antennas attached to the wireless APs. In order to obtain an omnidirectional gain from an isotropic antenna, energy lobes are pushed in from the top and the bottom, and forced out in a doughnut type pattern. If you continue to push in on the ends of the balloon (isotropic antenna pattern), a pancake effect with very narrow vertical beamwidth results, but with a large horizontal coverage. This type of antenna design can deliver very long communications distances, but has one drawback which is poor coverage below the antenna.
With the directional antennas, you can divert the RF energy in a particular direction to farther distances. Therefore, you can cover long ranges, but the effective beamwidth decreases. This type of antenna is helpful in near LOS coverage, such as covering hallways, long corridors, isle structures with spaces in between, etc. However, as the angular coverage is less, you cannot cover large areas. This is a disadvantage for general indoor coverage because you would like to cover a wider angular area around the AP. 59ce067264