Route Surveillance Research Articles

Wideband circularly polarized antenna with metallic walls for L-band applications

PurposeTo achieve right-hand circular polarization (RHCP), a 3-dB Wilkinson power divider with a λ/4 phase shifter is used. The crossed-dipoles are placed at almost λ/4 elevation on the ground plane and connected to two coaxial cables. Experiments show that the impedance bandwidth of 49.40% (913.7–1,513.1 MHz) and axial ratio bandwidth (ARBW) of 22.88% (1,145.8–1,441.8 MHz) are achieved.Design/methodology/approachIn this study, a wideband crossed-dipole antenna with circularly polarized (CP) radiation for L-band satellite and radar applications is presented. The proposed CP antenna comprises two orthogonally placed printed dipoles, a quadrature coupler and a box-shaped ground plane.FindingsFurthermore, by fixing the box-shaped ground plane under the radiators, 5.13 dBic RHCP peak gain at 1,300 MHz and maximum half-power beamwidth (HPBW) of 84.5° at 1,170 MHz are realized for the antenna.Originality/valueEight metallic walls are connected to four corners of the substrate to stabilize the radiation properties in this study. Results show that the ARBW and front-to-back ratio are improved and the maximum HPBW around 127° across the operating frequency band is achieved. The proposed CP antenna is a good candidate for Global Positioning System (GPS) L2 (1.227 GHz), GPS L5 (1.176 GHz) and air route surveillance radar system at 1,215–1,390 MHz frequency band.

Genomic Investigation of Salmonella Isolates Recovered From a Pig Slaughtering Process in Hangzhou, China.

The pig industry is the principal source of meat products in China, and the presence of pathogens in pig-borne meat is a crucial threat to public health. Salmonella is the major pathogen associated with pig-borne diseases. However, route surveillance by genomic platforms along the food chain is still limited in China. Here, we conducted a study to evaluate the dynamic prevalence of Salmonella in a pig slaughtering process in Hangzhou, Zhejiang Province, China. Fifty-five of 226 (24.37%) samples were positive for Salmonella; from them, 78 different isolates were selected and subjected to whole genome sequencing followed by bioinformatics analyses to determine serovar distribution, MLST patterns, antimicrobial resistance genes, plasmid replicons, and virulence factors. Moreover, phenotypic antimicrobial resistance was performed using the broth dilution method against 14 antimicrobial agents belonging to 10 antimicrobial classes. Our results showed that samples collected from the dehairing area (66.66%) and the splitting area (57.14%) were the most contaminated. Phenotypic antimicrobial resistance classified 67 of 78 isolates (85.90%) as having multidrug resistance (MDR), while the highest resistance was observed in tetracycline (85.90%; 67/78) followed by ampicillin (84.62%; 66/78), chloramphenicol (71.80%; 56/78), and nalidixic acid (61.54%; 48/78). Additionally, serovar prediction showed the dominance of Salmonella Typhimurium ST19 (51.28%; 40/78) among the 78 studied isolates, while plasmid prediction reported the dominance of IncHI2A_1 (20.51%; 16/78), followed by IncX1_1 (17.95%; 14/78) and IncHI2_1 (11.54%; 9/78). Virulence factor prediction showed the detection of cdtB gene encoding typhoid toxins in two Salmonella Goldcoast ST358 and one Salmonella Typhimurium ST19, while one isolate of Salmonella London ST155 was positive for genes encoding for the siderophore “yersiniabactin” and the gene senB encoding for enterotoxin production. From this study, we conclude that pig slaughterhouses are critical points for the dissemination of virulent and multidrug-resistant Salmonella isolates along the food chain which require the implementation of management systems to control the critical points. Moreover, there is an urgent need for the implementation of the whole genome sequencing platform to monitor the emergence of virulent and multidrug-resistant clones along the food chain.

Prevalence and genomic investigation of Salmonella isolates recovered from animal food-chain in Xinjiang, China

Salmonella is a major foodborne pathogen worldwide, causing serious cases of morbidity and mortality due to the consumption of contaminated foods. Animal-borne foods were considered the main source of transferring Salmonella to humans; however, route surveillance by genomic platforms along the food-chain is limited in China. Here, we proceeded to the application of whole genome sequencing in the epidemiological analysis of Salmonella isolated along the food-chain in Xinjiang, China. A total of 2408 samples were collected from farms, slaughterhouses, and markets, and subjected to the isolation of Salmonella strains. 314 (13.04%) of the samples were positive for Salmonella. Phenotypic antimicrobial resistance was conducted by the broth dilution method using 14 antimicrobial agents belonging to ten classes for all 314 isolates. A selection of representative 103 isolates was subjected to whole-genome sequencing for understanding the Salmonella diversity, including serovars, antimicrobial and virulence genes, plasmid types, multi-locus sequence types, and allelic types. We found that S. Agona was the dominant serovar and O:4(B) was the dominant serogroup. The dominant genotype was ST13 and each serovar has a unique MLST pattern. Plasmids prediction reported Col(MGD2)_1 and Col(Ye4449)_1 as the dominant plasmids, in addition to the detection of IncFII(S)_1 and IncFIB(S)_1 carried by all S. Enteritidis isolates. Importantly, virulence genes prediction showed the presence of cdtB gene encoding typhoid toxins, spv genes, and pef gene cluster encoding fimbriae in the genomes of S. Indiana and S. Enteritidis. Phenotypic antimicrobial resistance identified 92.04% of the sampled isolates as multi-drug resistance (MDR), with high resistance to tetracycline (78.03%; 245/314), amoxicillin/ clavulanic acid (75.80%; 238/314), and ampicillin (70.70%; 222/314). Together, we firstly reported the prevalence of MDR Salmonella isolates harboring critical virulence factors transmission via animal-borne food-chain in Xinjiang, hence route surveillance by whole-genome sequencing platform could facilitate recognition and project early warning for the emerging MDR clones along the food-chain.

北太平洋ルートにおける航空機対の水平重畳確率の推定

The safety of the North Pacific (NOPAC) route system has been evaluated using a collision risk model. This paper describes the method and results of the estimation of the lateral overlap probability which is a key parameter of the model. The probability was estimated from the empirical distribution of cross track deviations from the assigned track of a NOPAC route, namely R 220. The data obtained from air route surveillance radars together with flight plan data were used for the analyses. The estimated lateral overlap probability value for 100NM of lateral separation, Py (100) is 2.4x10^<-8>.

衝突危険度による洋上複合間隔ルートの安全性評価-I : NOPACルートの垂直方向の衝突危険度

This paper describes the method and results of safety assessment for the North Pacific (NOPAC) composite separation route system. The collision risk due to loss of vertical separation is estimated based on the observation data on the navigation performance of aircraft and traffic flow characteristics. In order to estimate various model parameters of the collision risk model(Reich model), the data on the tracks obtained by an air route surveillance radar(ARSR) and the traffic information extracted from the flight progress(flight plan) data were used for analyses. The result indicated that the vertical collision risk in the route system is less than the target level of safety(TLS) of the ICAO, i.e., 2.5×10^<-9> [fatal accidents/flying hour].

ARSR/NEXRAD Operational Comparison

The National Weather Service, Federal Aviation Administration, and Department of Defense are in the process of fielding the Next Generation Weather Radars (NEXRAD). It has been assumed that NEXRADs would provide a more accurate representation of the weather situation. However, because the NEXRAD’s scanning strategy is more time consuming than the Air Route Surveillance Radar (ARSR) weather data currently being used by air traffic controllers, there have been some concerns about its use in air traffic control. This article presents data assessing the relative ability of NEXRADs and ARSRs to detect and present significant weather in order to determine the operational impact of using NEXRAD data in lieu of ARSR data. © 1995 John Wiley & Sons, Inc.

Estimation Accuracy of Close Approach Probability for Establishing a Radar Separation Minimum

A Long-range Secondary Surveillance Radar (LSSR) has been developed and recently used as an Oceanic Route Surveillance Radar (ORSR) in Japan. The LSSR is an SSR (Secondary Surveillance Radar) only system for which the maximum coverage is 250 nautical miles (n.m.). This system utilizes monopulse azimuth estimation techniques for improving the accuracy of azimuth estimation.

Suppression of ground clutter using an X‐band radar

AbstractMost of the clutter received by an L‐band air route surveillance radar obeys Weibull distribution with various values of the shape parameters. The L‐band radar has a frequency of 1.3 GHz and pulsewidth of 3 μs. Hence, the spatial resolution is as large as 450 m. The X‐band radar, on the other hand, ns. frequency of 9.4 GHz and pulsewidth of 80 ns. The spatial resolution is as small as 12 m; we have found that the clutter amplitude distribution obeys a composite Weibull distribution when reflectors are ordinary terrain and such structures as buildings. Clutter suppression techniques for Weibull and non‐Weibull echos are proposed.

An all solid-state modulator for the ARSR-3 transmitter

This paper describes an all solid-state, high-power pulse modulator used in the ARSR-3 system (an FAA air route surveillance radar system). The modulator, the culmination of a number of years of both device and circuit development, uses fast switching Reverse Blocking Diode Thyristors (RBDT's) to directly switch 14-MW, 3-µs video pulses at high current without the use of magnetic switching aids. The modulator consists of five identical PFN modules, a trigger amplifier, and a pulse transformer which matches the modulator output to the beam characteristics of a klystron. Each module contains its own PFN, discharge RBDT switch assembly, and associated circuitry. This modulator is the first production equipment to use the new Westinghouse T62R RBDT devices. The devices switch 2200-A pulses with a turn-on rate of rise of up to 3000 A/µs.

Automated Ship Routing

The U.S. Navy's Fleet Numerical Weather Central has developed a numerical model to compute realistic time tracks for transoceanic shipping using short-range dynamic forecasts (40-72 hrs) and extended-range statistical forecasts to destination. This model resides in a computer program that is utilized by watch standers to prepare original routes and underway diversions for about 600 U.S. Navy ships a year. Global minimum time routes (GMTR) are computed twice daily for ships using optimum track ship routing (OTSR) service by this program, which considers navigation, environmental surveillance, environmental constraints, and ship performance curves. Maintenance of environmental surveillance and application of environmental constraints is accomplished through grids that represent the oceanic areas of the world and contain environmental parameters such as significant wave height and direction, frequency, fog, currents, and wind; however, any parameter or combination of parameters which can be represented numerically may be used in determining the GMTR. Comparison of the GMTR and the actual route sailed is possible by the computation of a post voyage verification route using actual environmental data. Ice areas are depicted (through the use of satellite data) and are utilized to constrain the global minimum time route selections. This is a description of the logic and the environmental parameters that produce the automated navigation, route surveillance, original route recommendations, and route verification.