New Mathematical Model for Wireless Signal Path Loss inside Buildings Nossire, Zyad; Dichter, Julius; Gupta, Navarun ...
2017 14th International Symposium on Pervasive Systems, Algorithms and Networks & 2017 11th International Conference on Frontier of Computer Science and Technology & 2017 Third International Symposium of Creative Computing (ISPAN-FCST-ISCC),
2017-June
Conference Proceeding
Mobile communications have evolved in a very rapid manner along with other fast-growing communication technologies. The widespread use of this technology has turned mobile communications into a life ...style. Thus the necessity for high quality and high capacity networks with thorough coverage has become one of the major demands. Many models have been proposed to cover the signal strength measurements and estimations, which make it easy to provide an efficient and reliable coverage area. One such model is the Okumura model, an accepted standard. In this paper we propose a new mathematical model for calculating the path loss inside buildings especially in elevators which are considered a very critical metropolitan feature where signal drops occur. In our work, radio wave propagation and frequency measurements were taken inside various buildings at the University of Bridgeport campus in Bridgeport CT, USA. These measurements were incorporated into the Okumura model to derive a new path loss model utilizing power measurements inside buildings. The experimental work shows very accurate and improved results for our model with respect to path loss detection inside elevators as compared to the Okumura model.
The cellular network coverage in sparsely populated and mountainous areas is often patchy. That can be a significant impediment for services based on connections between vehicles and their ...environment. In this paper, we present a method to reduce the waiting time occurring when a vehicle intends to send a message via a cellular network but is currently in a dead spot without sufficient coverage. We use a hybrid network approach combining cellular network access with ad-hoc networks between vehicles that are nearby. In particular, we introduce a data dissemination protocol that allows the vehicles connected through an ad-hoc network to find out which one will most likely leave the dead spot first. Messages can then be sent to this vehicle that forwards them as soon as it regains cellular network access. Further, we developed an initial implementation of this protocol using the technology WiFi Direct that is realized on many mobile phones. Implementation details of the prototype as well as analysis results regarding data transmission time limits of fast driving vehicles are discussed in the article as well.
RadioMap Kumar, Abhishek; Singh, Mridula; Yadav, Kuldeep ...
Proceedings of the Posters & Demos Session,
12/2014
Conference Proceeding
Poor signal quality results in frequent dropped calls, degradation of throughput, and high battery consumption. Coverage maps advertised by cellular operators are very abstract and provide coverage ...information for outdoor areas. In real-world, most of the cellular phone usage is reported indoors and therefore, call drops are more frequent in these environments. Aiming to provide seamless connectivity indoors, we develop a system RadioMap that uses sensing capabilities of a smartphone to create fine-grained cellular signal maps in indoor environments. These signal maps provide a low-cost and pervasive solution to the cellular operators for finding signal dead spots in indoor environments and accordingly, take rectifying measures such as installing signal boosters, etc.
Spring dead spot (SDS) (Ophiosphaerella spp.) causes damage to hybrid bermudagrass (Cynodon dactylon (L.) Pers. x transvaalensis Burtt Davy) grown in areas where winter dormancy occurs. The pathogen ...infects the stolons, rhizomes, and roots of warm-season grasses. Symptoms appear as circular, necrotic patches at spring greenup that reduce the playability and aesthetics of bermudagrass. Historically, fungicide efficacy against SDS has been inconsistent. There may be opportunities to improve application and post-application practices to mitigate the inconsistency. A study was conducted from 2019 to 2021 to examine the influence of post-application irrigation and soil surfactant on tebuconazole efficacy against SDS. The study was conducted at three locations: Virginia Tech Turfgrass Research Center (TRC), Blacksburg, VA; Independence Golf Club (IGC), Midlothian, VA; Nutters Crossing Golf Club (NCGC), Salisbury, MD. Tebuconazole was applied in the fall either once at 1.5 kg ai ha−1 or twice at 1.5 kg ai ha−1 two to four weeks apart when soil temperatures were between 10.7 and 21.8 °C. Treatments were applied with or without a soil surfactant and with or without 0.6 cm of post-application irrigation. Bermudagrass was assessed the following spring two or three times for patch number and percent SDS. Data were analyzed by assessment date, subjected to analysis of variance, and means were separated using Tukey's Honest Significant Difference test (P = 0.05). There were no treatment differences at IGC or NCGC in 2020 or 2021. At the TRC in both 2020 and 2021, results were inconsistent with tebuconazole generally suppressing SDS compared to the nontreated control. However, differences between tebuconazole-treated plots were variable. Our study suggests that including a soil surfactant with tebuconazole applications and/or irrigating post-application does not consistently increase SDS suppression.
•Tebuconazole was inconsistently effective against spring dead spot (SDS).•Soil surfactants inconsistently affected tebuconazole efficacy on SDS.•Post-application irrigation inconsistently affected tebuconazole efficacy on SDS.
Spring dead spot (SDS) (
spp.) is a soilborne disease of warm-season turfgrasses grown where winter dormancy occurs. The edaphic factors that influence where SDS epidemics occur are not well defined. ...A study was conducted during the spring of 2020 and repeated in the spring of 2021 on four 'TifSport' hybrid bermudagrass (
×
) golf course fairways expressing SDS symptoms in Cape Charles, VA, U.S.A. SDS within each fairway was mapped from aerial imagery collected in the spring of 2019 with a 20 MP CMOS 4k true color sensor mounted on a DJI Phantom 4 Pro drone. Three disease intensity zones were designated from the maps (low, moderate, high) based on the density of SDS patches in an area. Disease incidence and severity, soil samples, surface firmness, thatch depth, and organic matter measurements were taken from 10 plots within each disease intensity zone from each of the four fairways (
= 120). Multivariate pairwise correlation analyses (
< 0.1) and best subset stepwise regression analyses were conducted to determine which edaphic factors most influenced the SDS epidemic within each fairway and each year. Edaphic factors that correlated with an increase in SDS or were selected for the best fitting model varied across holes and years. However, in certain cases, soil pH and thatch depth were predictors for an increase in SDS. No factors were consistently associated with SDS occurrence, but results from this foundational study of SDS epidemics can guide future research to relate edaphic factors to SDS disease development.
Hybrid bermudagrass (Cynodon dactylon×C. transvaalensis) is widely used as turf in transition zone of China. Spring dead spot (SDS) is one of the most damaging diseases of hybrid bermudagrass. ...Symptoms of SDS appear when hybrid bermudagrass starts to break dormancy with warm temperature in early spring. The symptoms show sunken, circular or irregularly shaped, straw-colored patches, with 20 to 100 cm in diameter. The patches maintain dormant as the surrounding uninfected turfgrass resumes growth and turns green. SDS pathogens are soilborne fungi that colonize roots, stolons and rhizomes, infected roots or rhizomes become black and eventually collapse. Three species of fungi are reported to cause SDS: Ophiosphaerella herpotricha (Fr) J. Walker; O. korrae (J. Walker & A.M. Smith) Shoemaker & C.E. Babcock; or O. narmari (J. Walker & A.M. Smith) Wetzel, Hubert & Tisserat (Walker and Smith 1972; Walker 1980; Shoemaker and Babcock 1989; Wetzel et al. 1999). However, distribution of the three species may vary by geographical region (Cottrill et al. 2016). In October 2020, symptoms of SDS were observed on hybrid bermudagrass fairways of Taihu golf course in Wuxi, Jiangsu province. Root samples of SDS were collected, symptomatic roots with 3-4 cm length were cut, washed 2-3 times, surface sterilized in 0.6% NaOCl for 5 min, rinsed and blotted dry for 2 min and placed on potato dextrose agar (PDA) amended with 50 mg L-1 each of ampicillin, streptomycin sulfate and tetracycline. Plates were incubated in the dark at 25℃ for 5-7 days, Hyphae growing from the roots were transferred to new PDA plates. A total of 7 fungal isolates with morphology similar to SDS pathogens were obtained (Tredway et al. 2009). The genomic DNA was extracted from 2 of them (7-41, 8-6) and amplified with universal primers ITS5 and ITS4 (White et al. 1990). PCR products were sequenced (deposited as MW536995 and MW536994 in GenBank, not available yet) and showed 99.79% similarity to O. narmari (KP690979). Pathogenicity tests were performed on 'Tifdwarf' hybrid bermudagrass (9-week-old in 5 × 20 cm Cone-Tainers containing a sand and nutrition substrate mixture). Eight oat seeds infested with O. narmari were inserted 5 cm below the soil surface in the root zone of hybrid bermudagrass. The inoculated turfgrass grew for five weeks in the growth chamber with a 12-h day/night cycle of 25/20°C and 90% relative humidity. A control treatment was inoculated with 8 noninfested sterile oat seeds, and each treatment was replicated 3 times. The root tissues of hybrid burmudagrass inoculated with O. narmari became black and necrotic, no symptoms were observed on the roots of noninfested plants. O. narmari was consistently reisolated from symptomatic roots, and confirmed by PCR as mentioned above. To the best of our knowledge, this is the first report of O. narmari caused spring dead spot in the transition zone of China. The identification of SDS caused by O. narmari will have important implications for the management of this root-rot species on hybrid bermudagrass.
Accelerometers are becoming popular in sport performance, as they are easy to wear, affordable, and usable in the field. Eccentric chainrings have been commercialised to improve pedalling ...performance, but little is known about their possible effects in the first pedal strokes (PS) of maximal sprint starts. To analyse the effects of the Q-Ring chainring (Q) on pedalling mechanics and performance in the BMX starting hill, 12 Spanish-National-Team BMX athletes performed 3 maximal sprints comparing Q vs No-Q. Time was measured in the first three meters. Acceleration output was registered with a triaxial 6 g accelerometer (200 Hz) in the first four PS. Discrete time, acceleration and statistical parametric mapping (SPM) were used to compare between conditions. Q showed no improvement in performance, despite a force-application time increasing (p = 0.013, ES = 0.39) and a reduction in the dead spot time (p = 0.028, ES = −0.73). Time after the four PS was greater (p = 0.006, ES = 0.63), and 3-m time did not change. Likewise, SPM 1D comparison showed no differences along the four PS. Therefore, accelerometry confirms its potential to evaluate pedalling technique in BMX, where Q-Ring fails to improve the pedalling mechanics in the starting hill.
Spring dead spot (SDS) of bermudagrass (Cynodon dactylon) is primarily caused by Ophiosphaerella herpotricha and Ophiosphaerella korrae in North America. These two species respond differently to ...numerous management practices, grow optimally at different soil pH ranges, and differ in aggressiveness. Understanding the Ophiosphaerella species distribution in regions where SDS occurs will allow turfgrass managers to tailor their management practices toward the predominant species present. A survey was conducted in the Mid-Atlantic United States in which 1 to 14 samples of bermudagrass expressing SDS symptoms were taken from 51 athletic fields, golf courses, or sod farms across Delaware, Maryland, North Carolina, and Virginia. DNA was isolated from necrotic root and stolon tissue, amplified using species-specific primers, and detected in a real-time PCR assay. At least one isolate of O. herpotricha was recovered from 76% of the locations, and O. korrae was recovered from 73% of the locations. O. herpotricha was amplified from 55% of the samples, whereas O. korrae was amplified from 37% of the samples. There were distinct regions in the Mid-Atlantic in which either O. herpotricha or O. korrae was predominant. O. herpotricha was predominant in western Virginia, central North Carolina, Delaware, and eastern Maryland. However, O. korrae was predominant in central Maryland and Virginia as well as eastern Virginia and North Carolina. O. herpotricha was isolated from certain cultivars more frequently than O. korrae and vice versa. These survey results elucidate the geographic distribution of O. herpotricha and O. korrae throughout the Mid-Atlantic United States.
This paper provides the evidence of a sweet spot on the boot/foot as well as the method for detecting it with a wearable pressure sensitive device. This study confirmed the hypothesized existence of ...sweet and dead spots on a soccer boot or foot when kicking a ball. For a stationary curved kick, kicking the ball at the sweet spot maximized the probability of scoring a goal (58-86%), whereas having the impact point at the dead zone minimized the probability (11-22%). The sweet spot was found based on hypothesized favorable parameter ranges (center of pressure in x/y-directions and/or peak impact force) and the dead zone based on hypothesized unfavorable parameter ranges. The sweet spot was rather concentrated, independent of which parameter combination was used (two- or three-parameter combination), whereas the dead zone, located 21 mm from the sweet spot, was more widespread.
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