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This study is aimed at evaluating the adjacent band compatibility of single frequency multi-Global Navigation Satellite System (GNSS), consisting of the Global Positioning System (GPS) L1 coarse acquisition (C/A) and Galileo E1 open service (OS) signals. The study is conducted using GNSS simulation, which allows for the tests to be held with various repeatable conditions, as defined by the users. It is found that the factors that affect the level of disruption from adjacent band interference include GNSS receiver parameters, as well as carrier frequency and bandwidth of interference signals. GNSS receivers with lower receiver sensitivity and higher receiver noise would be more susceptible to adjacent band interference. Moving the carrier frequency of interference signals away from the frequency of the GNSS L1 / E1 band (1575.42 MHz) as well as increasing their bandwidths increase the power levels that affect GNSS performance. The GPS + Galileo mode has slightly improved performance against interference as compared to the GPS only mode due to the alternative binary offset carrier (AltBOC) modulation that is employed for the Galileo E1 OS signal, which is improves its robustness. [ABSTRACT FROM AUTHOR]

The study of groundwater resources in relation to topography is important. Clearly, in different topography, depth of the water level is different. Therefore, the aim of this study is the determination of the relationship between landform classes with compound topographic index (CTI) and depth of the water for the Maharlou-Bakhtegan watershed, Fars Province, Iran. In order to evaluate the depth of the water for the study area, CTI and geomorphology (landforms) were derived from a Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM). The results of landform classes extracted using topographic position index (TPI) showed that the largest landform is open slope, while the smallest are plains. It was found that CTI and depth of the water values are high in plain classes, while they are low in local ridges. High depth of the water were found to be mostly confined to the pit regions in the plain landform, because groundwater recharge occurs in the zones where standing water remains for sufficient long period of time and has favourable condition for recharge.

Due to long-distance propagation, the received Global Navigation Satellite System (GNSS) signal power is low, making it highly susceptible to signal interference. In safety-critical applications such as unmanned aerial vehicles (UAVs), GNSS signal interference can lead to significant position, navigation and timing (PNT) service deterioration or interruption. Therefore, this work focuses on investigating the effects of Global Positioning System (GPS) jamming on a DJI Mini 2 UAV and a Garmin GPSMAP 60CSx handheld GPS receiver based on various interference signal power levels and rotation angles. The field evaluation is conducted in an open area and GPS interference signals are generated using a signal generator. The signal is emitted to the target UAV using a directional antenna, and the effect of the signal is analysed and evaluated. Then, using the same setup, the measurement is repeated by varying the rotation angles of the UAV to 0, 45 and 90°. The findings indicate that when a jammer's signal reaches approximately -110 dBm in an outdoor setting, it significantly affects GPS accuracy. The impact of GPS jamming on rotation angles is influenced by altering the UAV's position (lateral and upright) as a result of changes in antenna orientation (facing upwards or towards the interference signal). [ABSTRACT FROM AUTHOR]

This paper is aimed at evaluating the effect of multipath on multi-Global Navigation Satellite System (GNSS) performance via GNSS simulation. The study is conducted for a Global Positioning System (GPS) receiver, Garmin GPSMAP 60CSx (Receiver R1), and two multi-GNSS receivers, Garmin GPSMAP 66sr (Receiver R2) and Trimble TDC600 (Receiver R3). Varying parameters of GNSS signal power attenuation and time delay are employed for multipath conditions of benign, moderate, challenging and difficult. It is found that with increasing severity of multipath, GNSS position error increases due to increase of GNSS signal power attenuation and time delay. Single frequency L1/E1 GPS only and GPS + Galileo modes are both affected by multipath, though in the case of Receiver R3, the GPS + Galileo mode provides some mitigation for multipath. [ABSTRACT FROM AUTHOR]

This study is aimed at investigating the relationship between landform classification and vegetation in the southwest of Fars province, Iran. First, topographic position index (TPI) is used to perform landform classification using a Shuttle Radar Topography Mission (SRTM) digital elevation model (DEM) with resolution of 30 m. The classification has ten classes; high ridges, midslope ridges, upland drainage, upper slopes, open slopes, plains, valleys, local ridges, midslope drainage and streams. Visual interpretation indicates that for the local, midslope and high ridge landforms, normalized difference vegetation index (NDVI) values and tree heights are higher as compared to the other landforms. In addition, it is found that there are positive and significant correlations betweenNDVI and tree height (r = 0.923), and landform and NDVI (r = 0.640). This shows that landform classification and NDVI can be used to predict tree height in the area. High correlation of determination (R2) 0.909 is obtained for the prediction of tree height using landform classification and NDVI.

With the growth of the population, the development of industrial, agricultural and so on, the amount of gas demand has been increasing steadily. Supplying the required gas energy often involves the construction of new power plants. The construction of power plants has social, economic, political and environmental consequences. Given the impact of power plant location in the cost of production and transmission of energy, environment, and so on, the importance of selecting the right place for the construction of the power plant is obvious. Therefore, in this study, geographical information system (GIS) based fuzzy-analytic hierarchy process (AHP) as one of the multicriteria decision methods and Dempster–Shafer theory (DST) methods are used to determine suitable locations for construction of gas power plant in Esfahan province, southwest of Iran. Different layers including distance to pipeline, distance to road, lithology, distance to stream, elevation, slope, and land use are prepared using ArcGIS. Subsequently, the importance of each factor in determining gas power plant location is defined using membership function. In the fuzzy-AHP method, membership function fuzzy maps for each layer are prepared. The DST model in Matlab is also used. The method was applied with three levels of confidence 99.5%, 99%, and 95% with the results compare. The results with the fuzzy method showed that 9.57% of the study area is unsuitable for the gas power location. On the hand, the results of the DST model showed that unsuitable areas for the DST method occupy 10.36%, 13.01%, and 19.55% of study area for levels of confidence of 95%, 99%, and 99.5%, respectively. [ABSTRACT FROM AUTHOR]

This paper is aimed at evaluating the performance of a Garmin GPSMAP 66sr multi-GNSS receiver via GNSS simulation. The study focuses on two important parameters in evaluating GNSS performance, namely performance under varying GNSS signal power levels and radio frequency interference (RFI). This study is conducted for the GPS L1 coarse acquisition (C/A) and Galileo E1 open service (OS) signals, for two conditions: 1) GPS only with six satellites (assuming an obstruction scenario with limited view of satellites); 2) GPS with six satellites and Galileo with six satellites. It is observed that at lower GNSS signal power levels and higher interference signal power levels, the higher number of GNSS signals observed for the GPS + Galileo mode allows it to have lower probable errors as compared to the GPS only mode. This highlights the advantage of multi- GNSS in degraded environments, such as dense urban and forest areas. [ABSTRACT FROM AUTHOR]

In this study, Global Positioning System (GPS) simulation is used to evaluate the performance of three commercial GPS speed meters: 1) S1: SkyRC GSM020; 2) S2: XOSS G+; and 3) S3: Magene C406. It is found that with decreasing GPS signal power level, speed errors increase due to decreasing carrier-to-noise density (C/N0) levels for GPS satellites tracked by the receiver, which is the ratio of received GPS signal power level to noise density. In addition, varying speed error patterns are observed for the each of the readings. This is due to the GPS satellite constellation being dynamic, causing varying GPS satellite geometry over location and time, resulting in GPS accuracy being location / time dependent It is found that the R3 receiver provided the lowest position errors for both the open area and obstruction area scenarios due to it having higher receiver sensitivity and lower receiver noise, which allows it track higher C/N0 levels for the available GPS satellites. All three GPS speed meters are found to have relatively similar speed errors. However, Speed Meter S1 is observed to be able to operate at lower GPS signal power levels as compared to the other speed meters. This could be as it higher receiver sensitivity and lower receiver noise, which allows it track higher C/N0 levels for the available GPS satellites. [ABSTRACT FROM AUTHOR]

This study is aimed at evaluating the vulnerabilities of unmanned aerial vehicles (UAVs) to Global Positioning System (GPS) jamming and spoofing. It is conducted for two commercial UAVs: Osman X28 (UAV A) and CSJ S167 (UAV B). The results obtained demonstrate that UAVs are susceptible to GPS jamming and spoofing even at relatively low power levels of interference / spoofing signals. Given the increasing proliferation of UAVs in various applications, attention should be given to addressing the security vulnerabilities of UAVs. [ABSTRACT FROM AUTHOR]

This study is aimed at evaluating Global Navigation Satellite System (GNSS) Space Service Volume (SSV) performance in terms of number of visible GNSS satellites. This study focuses on the two GNSS systems that currently have full operating capability (FOC), namely Global Positioning System (GPS) and Globalnaya Navigatsionnaya Sputnikovaya Sistema (GLONASS). The study is conducted using Trimble Planning, which is a mission planning tool used to predict GNSS coverage at a given location and time. It is observed that GPS and GLONASS can each provide continuous coverage for up to altitude of 8,000 km. Combined use of GPS and GLONASS allows for increased GNSS satellite availability at altitude of 8,000 km, and continuous coverage at altitude of 12,000 km. The availability then degrades with increasing altitude, due to increasingly poor GNSS satellite geometry. It is proposed that further studies be conducted via GNSS simulation, whereby the accuracy of GNSS readings at various altitudes can be measured. [ABSTRACT FROM AUTHOR]

This study is aimed at evaluating adjacent radio frequency band power levels that can be tolerated by the Global Positioning System (GPS) L1 coarse acquisition (C/A) signal and the extent to which such power levels impact GPS performance. The study is conducted using GPS simulation, which allows for the tests to be held with various repeatable conditions, as defined by the authors. It is found that the factors that affect the level of disruption from adjacent band interference include GPS signal power level, and carrier frequency and bandwidth of interference signals. Decreasing power levels of the GPS signal decreases the power levels and increases the range of frequencies of interference signals that affect the GPS signal. As the carrier frequency of the interference signals moves away from the frequency of the GPS signal (1575.42 MHz), the power levels required to affect the GPS signal increase. Furthermore, increasing bandwidths of interference signals increase the power levels but increase the range of frequencies that can affect the GPS signal. [ABSTRACT FROM AUTHOR]

The selection of competent tenderers in high-value projects and procurements is very critical, as it determines the risks and outcomes of the projects. In some government procurement systems, millions of dollars are at stakes. Unfortunately, a significant number of high-value projects and procurements have failed to achieve the intended goals and standards due to incompetent tenderers. Hence, employing the right decision making approach in the tender evaluation and selection process is vital. This study evaluates the use of analytical hierarchy process (AHP) for technical tender evaluation using a case study. The findings show that AHP is more effective than the present method which employs the scoring and weighted sum model. AHP also provides more accurate results with minimal bias. It is expected that the findings of this study will be beneficial to improve the existing procurement system. In general, the findings may also be applicable and beneficial to other highvalue government procurement systems. [ABSTRACT FROM AUTHOR]

This study is aimed at evaluating the effect of Global Positioning System (GPS) antenna orientation for three Garmin GPS receivers that use built-in quad helix antennas; GPSmap 60CSx, GPSmap 62Cs and Oregon 550. The study is conducted using GPS simulation, which allows for the tests to be held with various repeatable conditions, as defined by the authors. Readings are taken for GPS antenna orientations of 0 to 345°, at increments of 15°. From the results obtained, it is found that there is degradation of accuracy for orientations of 75 to 120° and 240 to 285°. For the remaining orientations, the accuracy remains constant. This indicates that the quad helix antennas are operating in endfire and backfire modes simultaneously. While this type of design has smaller antenna gain than quad helix antennas that use only endfire or backfire modes, it allows for a more isotropic antenna performance. This study will be extended to evaluate the performance of antennas of a wider range of GPS receivers. [ABSTRACT FROM AUTHOR]

In this study, the Mazandran River watershed is selected for detailed morphometric analysis. Morphometric analysis for parameters of stream number (Nu), stream orde (U ), cumulative length of streams (L), bifurcation rati (Rb), watershed relief (Bb), drainage density (Dd), stream frequency (Rf), form factor (Rf), circularity rati (Rb) and elongation rati (Rb) is carried out to describe the drainage properties of the three subwatersheds in the study area (W1, W2 and W3). The results show that among the subwatersheds, the highest Nu is 333 (stream order 1 for W1), while the lowest Nu is 1 (stream order 4 for W1). For U, among the subwatersheds, W1 and W2 are of order 3, and W3 is of order 4, showing that they are in the early stages of erodibility. W1 has the highest L of streams (5.72 km), whereas W3 has the lowest L of streams (3.11 km). The Rb values for the subwatersheds are between 0.73 to 1.84, whie Dd varies between 0.0055 and 0.0060 km/km2. The results also show that the Fs values for the subwatersheds exhibit positive correlations with Dd (from 0.48 to 0.58). The minimum and maximum form factors (Rf) are observed for W3 (0.58) and W2 (0.93) respectively, indicating W2 is more round, resulting in lower lag time. Rc is in the range of 0.43 to 0.75. The overall results indicate that in the subwatersheds are have high erodibility and need more management. [ABSTRACT FROM AUTHOR]

In this study, fuzzy analytic hierarchy process (AHP) is used to study the relationship between drinking water quality and landform classes in south of Firozabad, east of Fars province, Iran. For determination of drinking water quality, parameters of calcium (Ca), chlorine (Cl), magnesium (Mg), thorium (TH), sodium (Na), electrical conductivity (EC), sulfate (So4) and total dissolved solids (TDS) were used. It was found that 8.29 % of the study area have low water quality; 64.01 %, moderate; 23.33 %, high; and very high, 4.38 %. Areas with suitable drinking water quality are located in parts of the southeast and southwest parts of the study area. The relationship between landform class and drinking water quality show that drinking water quality is high in the stream, valleys, upland drainages and local ridge classes, and low in the plain small and midslope classes. [ABSTRACT FROM AUTHOR]

In this research, the relationship between classes of landform, and electrical conductivity (EC) of soil and water in the Shiraz Plain, Fars province Iran was investigated using a combination of geographical information system (GIS) and fuzzy model. The results of the fuzzy method for water EC showed that 36.6% of the land to be moderately land suitable for agriculture; high, 31.69%; and very high, 31.65%. In comparison, the results of the fuzzy method for soil EC showed that 24.31% of the land to be as not suitable for agriculture (low class); moderate, 11.78%; high, 25.74%; and very high, 38.16%. In the total, the land suitable for agriculture with low EC is located in the north and northeast of the study area. The relationship between landform and EC shows that EC of water is high for the valley classes, while EC of soil is high in the upland drainage class. In addition, the lowest EC for soil and water are in the plain small class. [ABSTRACT FROM AUTHOR]

The aim of this study is to cluster landforms in the west of the Fars province, Iran using selforganizing maps (SOM). According to qualitative data, the clustering tendencies of landforms are investigated using six morphometric parameters, which are slope, profile, plan, elevation, curvature and aspect. First, topographic position index (TPI) is used to prepare the landform classification map. The results of SOM show that there are five classes for landform classification in the study area. Cluster 5 corresponds to high slope, high elevation but with different of concavity and convexity that consist of ridge landforms, while Cluster 3 corresponds to flat areas, possibly plantation areas, in medium elevation and almost flat terrain. Clusters 1, 2 and 4 correspond to channels with different slope conditions. [ABSTRACT FROM AUTHOR]

In this study, we investigate the use of morphometric parameters and fuzzy membership functions to perform landform classification for different case areas of Zagros Mountains from digital elevation models (DEMs). First, multiscale DEMs with scales of 5 to 45 cells are generated using the lifting scheme. The maximum curvature for the scale of five cells has the lowest standard deviation, and hence, is determined to be the characteristic scale. Data layers are produced from the DEM of this scale for slope, minimum and maximum curvatures, and plan and profile curvatures. The fuzzy membership rules for these data layers are used to determine the landform classes. Comparison of the results of landform classification using the fuzzy classification method and topographic position index (TPI) with the geology map of the study area show that the fuzzy classification method provides higher accuracy (81 %) as compared to TPI (42 %). This is because for the fuzzy classification method, sloping areas are separated into sloping and non-sloping areas, and the membership functions are defined to prevent landforms belonging to the sloping areas from being classified in the non-sloping areas and vice versa. [ABSTRACT FROM AUTHOR]

Wireless spy devices (WSDs) are surveillance equipment, such as listening bugs or cameras, hidden in objects or covertly placed in rooms. Surveillance using WSDs is one of the main methods of recording conversations for both intelligence gathering as well as criminal charges. However, WSDs have also been abused for nefarious purposes, such as industrial espionage and blackmail. This paper is aimed at reviewing WSD technologies, in terms of types, energy sources and modes of operations. Methods used for detecting WSDs, focusing on radio frequency (RF) detectors, spectrum analysis and nonlinear junction detectors (NLJDs), are also be discussed. [ABSTRACT FROM AUTHOR]

The derivation of spatial significance is an important aspect of geospatial analysis and hence, various methods have been proposed to compute the spatial significance of entities based on spatial distances with other entities within the cluster. This paper is aimed at studying the spatial significance of mountain objects extracted from multiscale digital elevation models (DEMs). At each scale, the value of spatial significance index SSI of a mountain object is the minimum number of morphological dilation iterations required to occupy all the other mountain objects in the terrain. The mountain object with the lowest value of SSI is the spatially most significant mountain object, indicating that it has the shortest distance to the other mountain objects. It is observed that as the area of the mountain objects reduce with increasing scale, the distances between the mountain objects increase, resulting in increasing values of SSI. The results obtained indicate that the strategic location of a mountain object at the centre of the terrain is more important than its size in determining its reach to other mountain objects and thus, its spatial significance. [ABSTRACT FROM AUTHOR]

This study is aimed at addressing a mistake made in the authors' previous paper on Global Positioning System (GPS) static multipath simulation (Dinesh et al., 2013), whereby it was indicated that GPS performance is repeatable for every GPS satellite orbital pass of approximately 11 h, 58 min. GPS satellites only return to the original positions with respect to the earth at every two GPS satellite orbital passes of approximately 23 h, 56 min, and hence, GPS performance is only repeatable for that period. This study demonstrates the repeatability of GPS performance with respect to GPS satellite orbital passes. It is further extended to verify the findings in Dinesh et al. (2013) in regards to GPS performance in various static multipath conditions. [ABSTRACT FROM AUTHOR]

Global Navigation Satellite Systems (GNSS) are being increasingly used for a variety of important applications, including public safety services (police, fire, rescue and ambulance), marine and aircraft navigation, vehicle theft monitoring, cargo tracking, and critical time synchronisation for utility, telecommunications, banking and computer industries. At present, there are two types of GNSS signals; military GNSS signals (L1 P(Y) and L2 P(Y) for the case of GPS, and L1 for GLONASS) and civilian GNSS signals (L1 coarse acquisition (C/A) .for GPS, and standard precision (SP) for GLONASS). Usage of L1 P(Y) and L2 P(Y), and HP signals are limited to the US and Russian militaries respectively. Other users only have access to civilian GNSS signals. Usage of civilian GNSS signals is growing rapidly due the quality of service provided by GNSS, ease of use and low user cost. However, unlike military GNSS signals, civilian GNSS signals are unencrypted and unauthenticated, making them vulnerable to spoofing, which refers to forging and transmission of navigation messages in order to manipulate the navigation solutions of GNSS receivers. Spoofing of civilian GNSS signals is surprisingly simple to conduct by even relatively unsophisticated adversaries. Due to the increasing reliance of various industries on GNSS, the consequences of GNSS spoofing can be severe, in terms of safety, environmental and economic damage. Hence, GNSS vulnerability mitigations steps should be given emphasis, including positioning/navigation / timing (PNT) backups, making full use of on-going GNSS modernisation programmes, inference detection & monitoring (IDM), and counter-spoofing technologies. This paper is aimed at reviewing the vulnerability of civilian GNSS signals to spoofing and the steps that can be taken to mitigate this vulnerability. [ABSTRACT FROM AUTHOR]