High Area Coverage Research Articles

A soft and stretchable bilayer electrode array with independent functional layers for the next generation of brain machine interfaces

Objective. Brain-Machine Interfaces (BMIs) hold great promises for advancing neuroprosthetics, robotics, and for providing treatment options for severe neurological diseases. The objective of this work is the development and in vivo evaluation of electrodes for BMIs that meet the needs to record brain activity at sub-millimeter resolution over a large area of the cortex while being soft and electromechanically robust (i.e. stretchable). Approach. Current electrodes require a trade-off between high spatiotemporal resolution and cortical coverage area. To address the needs for simultaneous high resolution and large cortical coverage, the prototype electrode array developed in this study employs a novel bilayer routing of soft and stretchable lead wires from the recording sites on the surface of the brain (electrocorticography, ECoG) to the data acquisition system. Main results. To validate the recording characteristics, the array was implanted in healthy felines for up to 5 months. Neural signals recorded from both layers of the device showed elevated mid-frequency structures typical of local field potential (LFP) signals that were stable in amplitude over implant duration, and also exhibited consistent frequency-dependent modulation after anesthesia induction by Telazol. Significance. The successful development of a soft and stretchable large-area, high resolution micro ECoG electrode array (lahrμECoG) is an important step to meet the neurotechnological needs of advanced BMI applications.

Adata-driven framework for introducing predictive analytics into expanded program on immunization in Pakistan.

Pakistan has anationwide expanded program on immunization (EPI), yet vaccination coverage in Pakistan is quite low. Recently, an analytical model has been proposed to improve the coverage by identifying children who are most likely to miss any of the vaccines included in the immunization schedule, known as defaulters; however, anumber of limitations remain unresolved in the previously proposed model. Firstly, it only classified children into two stages: defaulters and non-defaulters, considering all children at high risk of defaulting even if only one dose is missed. Secondly, there was no categorisation of high and low coverage areas for prioritised vaccination. The aim of this study was to propose aprediction framework for the accurate identification of defaulters. We have utilised asample dataset extracted from the Pakistan Demographic and Health Survey (PDHS, 2017-2018). This contained 7153 data records with 19demographic and socioeconomic attributes, which were used for defaulter prediction and the identification of association rules to understand the relation between demographics of the child and the vaccination status. Using amultilayer perceptron (MLP) classifier, the proposed model achieved 98% accuracy and 0.994 for the area under the curve (AUC), to correctly identify the children who are likely to default from immunization series at different risk stages. The proposed framework in this study is astep forward towards adata-driven approach and provides aset of machine learning techniques to utilise predictive analytics. Hence, this can reinforce immunization programs by expediting targeted action to reduce drop-outs.

Emergence of behavioural avoidance strategies of malaria vectors in areas of high LLIN coverage in Tanzania

Despite significant reductions in malaria transmission across Africa since 2000, progress is stalling. This has been attributed to the development of insecticide resistance and behavioural adaptations in malaria vectors. Whilst insecticide resistance has been widely investigated, there is poorer understanding of the emergence, dynamics and impact of mosquito behavioural adaptations. We conducted a longitudinal investigation of malaria vector host choice over 3 years and resting behaviour over 4 years following a mass long-lasting insecticidal nets (LLINs) distribution in Tanzania. By pairing observations of mosquito ecology with environmental monitoring, we quantified longitudinal shifts in host-choice and resting behaviour that are consistent with adaptation to evade LLINs. The density of An. funestuss.l., declined significantly through time. In tandem, An. arabiensis and An. funestuss.l. exhibited an increased rate of outdoor relative to indoor resting; with An. arabiensis reducing the proportion of blood meals taken from humans in favour of cattle. By accounting for environmental variation, this study detected clear evidence of intra-specific shifts in mosquito behaviour that could be obscured in shorter-term or temporally-coarse surveys. This highlights the importance of mosquito behavioural adaptations to vector control, and the value of longer-term behavioural studies.

Landslide data mosaicking based on an airborne laser point cloud and multi-beam sonar images

Landslides are one of the most disastrous geological hazards in southwestern China. Once a landslide becomes unstable, it threatens the lives and safety of local residents. However, empirical studies on landslides have predominantly focused on landslides that occur on land. To this end, we aim to investigate ashore and underwater landslide data synchronously. This study proposes an optimized mosaicking method for ashore and underwater landslide data. This method fuses an airborne laser point cloud with multi-beam depth sounder images. Owing to their relatively high efficiency and large coverage area, airborne laser measurement systems are suitable for emergency investigations of landslides. Based on the airborne laser point cloud, the traversal of the point with the lowest elevation value in the point set can be used to perform rapid extraction of the crude channel boundaries. Further meticulous extraction of the channel boundaries is then implemented using the probability mean value optimization method. In addition, synthesis of the integrated ashore and underwater landslide data angle is realized using the spatial guide line between the channel boundaries and the underwater multi-beam sonar images. A landslide located on the right bank of the middle reaches of the Yalong River is selected as a case study to demonstrate that the proposed method has higher precision than traditional methods. The experimental results show that the mosaicking method in this study can meet the basic needs of landslide modeling and provide a basis for qualitative and quantitative analysis and stability prediction of landslides.

Vegetation Growth Status and Topographic Effects in the Pisha Sandstone Area of China

Fractional vegetation coverage (FVC) plays an important role in monitoring vegetation growth status and evaluating restoration efforts in ecological environments. In this study, FVC was calculated using a binary pixel model and analyzed in the Pisha Sandstone area of China, using MODIS-EVI data from 2000 to 2019. Topographic effects were analyzed from elevation, slope and aspect using a terrain niche index model. The results were as follows. (1) From 2000 to 2019, FVC in the Pisha Sandstone area of China gradually increased at a mean rate of 0.0074/a, and the growth status of vegetation gradually improved. (2) The spatial distribution of FVC steadily decreased from southeast to northwest. FVC was the lowest in bare parts of the Pisha Sandstone area, whereas those in the sand- and soil-covered parts were the middle and highest, respectively. (3) With increasing elevation, the inferior coverage area and terrain niche index increased, and inferior coverage distribution changed from non-dominant to dominant. Meanwhile, the low, medium and high coverage areas decreased, and their distributions changed from dominance to non-dominance. (4) With increasing slope, distributions of the inferior, medium and high coverage areas changed from dominant to non-dominant, while the low coverage area had a dominant distribution. (5) Analyses of aspect effects revealed that the inferior coverage area was the dominant distribution in shady slopes but was non-dominant in semi-shady, semi-sunny and sunny slopes. The low, medium and high coverage areas were non-dominant in shady slopes, but dominant in semi-shady, semi-sunny and sunny slopes.

Responses of soil total phosphorus to freeze and thaw cycles in a Mollisol watershed

Freeze-thaw cycles (FTCs) change soil physiochemical properties and biogeochemical processes and inevitably influence the spatial distribution of soil phosphorus (P). In this study, a field investigation was conducted on the Mollisol soil of the Guangrong watershed from 2016 to 2018 to clarify the effect of FTCs on the spatial distribution of total phosphorus (TP) at soil depths of 0–5, 5–10 and 10–20 cm. A laboratory incubation experiment was conducted to reveal the effect of FTCs on TP in soil profiles (0–30 cm) in Mollisols. The results showed that (1) the spatial autocorrelation (nugget to sill ratio) of TP decreased by 5.92% after the FTCs while the spatial variance (coefficient of variation) increased by 17.19%. The TP in 85% of the watershed area decreased after the FTCs, and the mean content of TP decreased by 9.53%. These changes were mainly influenced by land use types, topographical factors, soil properties and human activities. (2) TP increased in the intersection between farmland and forestland (0.01 g kg−1) after the FTCs, while TP decreased both in the areas near the hydrological channel (0.06 g kg−1) and at the outlet of the watershed (0.13 g kg−1). Compared with down-slope tillage, maize planting, south-facing slopes and low vegetation coverage areas, the cross-slope tillage, soybean planting, north-facing slopes and high vegetation coverage areas reduced TP losses by 56.1%, 19.5%, 115.8% and 141.9%, respectively, in the 0–20 cm soil layer. (3) The effects of FTCs on TP in soil profile were mainly influenced by the soil moisture content, FTC frequency and soil bulk density in the laboratory incubation experiment. TP variability showed a V-shaped trend as the number of FTCs increased, and decreased as the initial moisture content increased at 1.1 g cm−3 of soil bulk density. (4) An equation based on the TP and mean value of normalized difference snow index, normalized difference vegetation index, ferrous minerals index and normalized difference soil moisture index from the freezing period to the thawing period was built to roughly predict the TP after FTCs (R2 = 0.72). Generally, the TP tended to decrease during both the freezing stage and the thawing stage in the field. Areas with down-slope tillage, existing maize fields, south-facing positions, low vegetation coverage and high snow coverage should be focused on to reduce P losses during FTCs.

Health workers\u2019 perceptions and challenges in implementing meningococcal serogroup a conjugate vaccine in the routine childhood immunization schedule in Burkina Faso

BackgroundMeningococcal serogroup A conjugate vaccine (MACV) was introduced in 2017 into the routine childhood immunization schedule (at 15–18 months of age) in Burkina Faso to help reduce meningococcal meningitis burden. MACV was scheduled to be co-administered with the second dose of measles-containing vaccine (MCV2), a vaccine already in the national schedule. One year following the introduction of MACV, an assessment was conducted to qualitatively examine health workers’ perceptions of MACV introduction, identify barriers to uptake, and explore opportunities to improve coverage.MethodsTwelve in-depth interviews were conducted with different cadres of health workers in four purposively selected districts in Burkina Faso. Districts were selected to include urban and rural areas as well as high and low MCV2 coverage areas. Respondents included health workers at the following levels: regional health managers (n = 4), district health managers (n = 4), and frontline healthcare providers (n = 4). All interviews were recorded, transcribed, and thematically analyzed using qualitative content analysis.ResultsFour themes emerged around supply and health systems barriers, demand-related barriers, specific challenges related to MACV and MCV2 co-administration, and motivations and efforts to improve vaccination coverage. Supply and health systems barriers included aging cold chain equipment, staff shortages, overworked and poorly trained staff, insufficient supplies and financial resources, and challenges with implementing community outreach activities. Health workers largely viewed MACV introduction as a source of motivation for caregivers to bring their children for the 15- to 18-month visit. However, they also pointed to demand barriers, including cultural practices that sometimes discourage vaccination, misconceptions about vaccines, and religious beliefs. Challenges in co-administering MACV and MCV2 were mainly related to reluctance among health workers to open multi-dose vials unless enough children were present to avoid wastage.ConclusionsTo improve effective administration of vaccines in the second-year of life, adequate operational and programmatic planning, training, communication, and monitoring are necessary. Moreover, clear policy communication is needed to help ensure that health workers do not refrain from opening multi-dose vials for small numbers of children.

A Study of the Interaction of Human Smart Characteristics with Demographic Dynamics and Built Environment: The Case of Limassol, Cyprus

The smart city notion provides an integrated and systematic answer to challenges facing cities today. Smart city policy makers and technology vendors are increasingly stating their interest in human-centered smart cities. On the other hand, in many studies smart city policies bring forward a one-size-fits-all type of recommendation for all areas in question instead of location-specific ones. Based on the above considerations, this paper illustrates that smart citizen characteristics, alongside local urban challenges, are paving the way towards more effective efforts in smart city policy decision making. Our main presumption is that the development level of human-centered indicators of smart cities varies locally. The scientific objective of this paper is to find a simple, understandable link between human smart characteristics and local determinants in Limassol city, Cyprus. The data set consists of seven indicators defined as human smart characteristics and seven which determine local urban challenges consisting of demographic dynamics and built infrastructure attributes based on housing. Correlations of the 14 above indicators are examined in entirety and separately, as the study area was divided into three spatial sub-groups (high, moderate, and low coverage areas) depending on dispersed urbanization, as the main challenge of the study area. The data were obtained mainly from the most recent population census in 2011 and categorized in sub-groups by triggering CLC 2012. Analyzing the statistics using principal component analysis (PCA), we identify significant relationships between human smart city characteristics, demographic dynamics and built infrastructure attributes which can be used in local policy decision making. Spatial variations based on the dispersed urbanization are also observed regarding the above-mentioned relationships.

Integrated Numerical-Experimental Assessment of the Effect of the AZ31B Anisotropic Behaviour in Extended-Surface Treatments by Laser Shock Processing

In recent years, an increasing interest in designing magnesium biomedical implants has been presented due to its biocompatibility, and great effort has been employed in characterizing it experimentally. However, its complex anisotropic behaviour, which is observed in rolled alloys, leads to a lack of reliable numerical simulation results concerning residual stress predictions. In this paper, a new model is proposed to focus on anisotropic material hardening behaviour in Mg base (in particular AZ31B as a representative alloy) materials, in which the particular stress cycle involved in Laser Shock Processing (LSP) treatments is considered. Numerical predictions in high extended coverage areas obtained by means of the implemented model are presented, showing that the realistic material’s complex anisotropic behaviour can be appropriately computed and—much more importantly—it shows a particular non-conventional behaviour regarding extended areas processing strategies.

School-based vaccination programmes: An evaluation of school immunisation delivery models in England in 2015/16

Schools are increasingly being used to deliver vaccines. In 2015/16 three school-based vaccination programmes were delivered to adolescents in England: human papillomavirus (HPV), meningococcal groups A, C, W and Y disease (MenACWY) and tetanus, diphtheria and polio (Td/IPV). We assessed how school delivery models impact vaccine coverage and how a delivery model for one programme may impact another. Routinely collected national data were analysed to ascertain the school grade achieving highest coverage within each one-dose programme and to compare two-dose delivery models (within year vs across years) for the HPV vaccine. We also assessed whether the HPV delivery model was associated with coverage in other programmes.MenACWY and Td/IPV coverage was highest in younger school grades. Overall similar HPV coverage was achieved with both models (86.7% two doses within one year, 85.8% two doses across two years, p = 0.20). High two-dose HPV coverage in 2015/16 was reported in areas that achieved high HPV coverage in 2013/14 when three doses were required. Areas with high three-dose coverage in 2013/14 achieved higher coverage with a within-one-year approach (92.0% vs 85.2%, p < 0.001), whilst areas reporting low coverage in 2013/14 achieved lower but similar coverage in 2015/16 with both models (79.2% vs 80.9% p = 0.29). MenACWY and Td/IPV coverage were higher in areas with high HPV coverage in 2013/14. Among high HPV coverage areas, MenACWY coverage was higher when HPV doses were delivered within year.School-based programmes should be offered as early as feasible and acceptable to optimise coverage. The choice of delivery model for HPV should take into account local performance and provider experience. Single providers may delivery multiple vaccines and the delivery for one programme may affect the performance of other programmes. Providers should consider local circumstances including past and current vaccine coverage and factors influencing coverage when deciding what delivery model to adopt.

Medium range sea ice prediction in support of Japanese research vessel MIRAI’s expedition cruise in 2018

ABSTRACT The Japanese research vessel MIRAI sailed into the Arctic Ocean through the Bering Strait from 4 to 25 November 2018 to study the atmosphere, ocean, and sea ice of the Chukchi Sea. Early winter dynamics and thermodynamics can cause sea ice conditions to change over short timescales. Heavy ice pressure may build up in the compression of compact ice. MIRAI is an ice-strengthened ship that has to avoid thick sea ice and areas of high sea ice coverage, and therefore precise medium-range forecast of sea ice distribution is key to its safe and efficient navigation. A high-resolution (about 2.5 km) coupled ice–ocean model was used to produce medium-range (10-day) forecasts for the expedition. European Center for Medium-Range Weather Forecast’s atmospheric model high-resolution 10-day forecast was used as forcing data. Forecast skill is measured by ice edge error, which is the average distance between forecast and observed ice edges. Using a threshold of 15% sea ice concentration to indicate the ice edge, the maximum ice edge error in the ice–ocean coupled model in the Chukchi Sea is 16 km, indicating that the model is able to provide 10-day forecasts with sufficient accuracy for the vessel’s operation.

High efficiency perovskite solar cells using nitrogen-doped graphene/ZnO nanorod composite as an electron transport layer

We demonstrate for the first time, the photovoltaic performance of perovskite solar cells (PSCs) by employing nitrogen-doped graphene/ZnO nanorod nanocomposites (NG-ZnO NR NCs) as an electron transport layer (ETL). A series of PSCs are fabricated by varying the NG concentration from 0 to 1 wt% with an increment of 0.2 wt% in ZnO NRs having a device structure of FTO/NG-ZnO NR NCs/CH3NH3PbI3/Spiro-MeOTAD/Ag. The perovskite films grown on NG-ZnO NR NCs exhibited a uniform film with high surface coverage area with an improved crystallinity. By employing photoluminescence measurements, it was found that NG-ZnO NR NCs reduced the interfacial resistance by improving charge carrier extraction, which is in correlation with an improvement in photocurrent and fill factor in the corresponding devices. At an optimized concentration of NG (0.8 wt%) in ZnO NRs, PSCs obtained an improvement in photocurrent from 17.38 mA/cm2 to 21.98 mA/cm2 and the power conversion efficiency from 12.87% to 16.82%, respectively.

Socio-economics of wheat production in Kailali and Sunsari districts of Nepal

For socio-economic assessment on wheat production, research was conducted from March to June, 2019 in two major wheat growing districts of Nepal, Kailai and sunsari. The primary information was collected by face to face interview using the pre-tested semi-structured interview schedule, two Key Informant Surveys were also done.In addition, the secondary information were collected from the review of related literatures. The survey areas were selected by consultating with Agriculture Knowledge Centre and agricultural officials of the local government; sample were selected by using simple random sampling. All total, 194 samples were selected for this study; the outliers and incomplete responses were omitted. The descriptive statistics revealed that Nepal 297 (66.16 %) has the highest area coverage in Sunsari while Gautam (36.50%) has the highest coverage in Kailali. Multiple regression model revealed that wheat cultivated area (p= 0.000), adoption of NARC released varieties (p= 0.000), gender of the household head (p= 0.017), age of the household head (p= 0.040), membership of organization (p= 0.094) and number of family members between age group 15 to 59 years (p= 0.085) have significant effect on wheat production. Furthermore, the unpaired t-test showed that the mean productivity of wheat in Kailali (2.99 Mt./ha) is significantly higher than that of Sunsari (2.81t./ha) at 5% level of significance. To increase the wheat productivity, the concerned government agricultural institutions should: assure access to NARC released improved varieties, make policy to consolidate the fragmented land, encourage the economically active population and the household heads towards wheat production by providing the efficient technical and financial support.

CELLULAR NETWORK RESOURCE DISTRIBUTION METHODS FOR THE JOINT SERVICING OF REAL-TIME MULTISERVICE TRAFFIC AND GROUPED IOT TRAFFIC

Immense growth in the volumes and multiplicity of data to be collected in future Internet of Things (IoT) applications is one of the crucial challenges for the networking organizations as they develop from 4G+ to true 5G systems. Particularly bulk of this traffic includes complex, unstructured and varied data (Big Data) evolve from smart networking ecosystems (LTE-devices, NB-IoT devices). Although 5G offers many low power wide area technologies (Lora WAN, GSM and NB-IoT etc.), principally NB-IoT seems very promising addressing the problem because of its certain characteristics like high fault tolerance, delay tolerance, higher coverage area etc. However, due to the limited bandwidth (180 kHz) availability one of the challenges is how to efficiently use these resources to support and handle massive number of growing IoT devices, also resource management and allocation methodology between LTE and NB-IoT traffic flows. In this context, several key issues for IoT communications in 5G networks should be addressed to satisfy quality of service (QoS) provisioning. In this paper, we proposed a mathematical model for Operator Surveillance systems for sharing radio resources between LTE and NB-IoT. The model utilizes the technique of network slicing for resource management. The proposed techniques provide scenarios that aims to offer a trade-off between the two types of traffics by guaranteeing the network performance and avoiding unproductive utilization of available resources.

Beam-Switching High Gain CP Graphene ME-Dipole Antenna for 5G MIMO Communications

A wideband circularly polarized (CP) graphene-based magneto-electric (ME) antenna with reconfigurable radiation characteristics for 5G MIMO communications is presented in this paper. It consists of graphene patches deposited on silicon oxide substrate arranged horizontally and vertically to act as a ME-antenna. The reconfigurable conductivity of graphene is used to control the operating bandwidth of the antenna. The single element has an impedance matching bandwidth of 78.3 % with the circular polarized band of 61.2% for applying chemical potential, µc=2 eV. The effect of changing the graphene reconfigurable conductivity on the radiation characteristics of the ME-antenna is investigated. The operating bandwidth is controlled by proper biasing the graphene sheet. The peak gain and the antenna efficiency are increased with increasing the chemical potential value due to the increase in graphene conductivity. The mutual coupling between ME-antenna elements is investigated for linear and circular arrangement. Octagonal array consists of 8-similar elements are constructed to produce electronic beam switching in different directions. Single beam, dual-beams, and omni-directional beam is achieved by controlling the graphene conductivity of single, two, and all the ME-elements in the array. Three ring array are designed to switch the beam in different angles for highest coverage area.

Reliability of direct varicella zoster virus loop-mediated isothermal amplification method for rapid diagnosis of breakthrough varicella

BackgroundSince patients with breakthrough varicella (BV) have mild symptoms, clinical diagnosis is difficult. In high vaccine coverage area, as BV occurs sporadically, point of care test is required for controlling varicella outbreak. In this study, the reliability of varicella zoster virus (VZV)-loop mediated isothermal amplification (LAMP) was evaluated for the rapid diagnosis of BV. Study designA total of 328 swab samples collected from patients with suspected varicella were analyzed. For the laboratory diagnosis of varicella, VZV real-time PCR was carried out using DNA extracted from swab samples. Swab samples without DNA extraction were used for VZV-LAMP(direct-LAMP). ResultsVZV infection was diagnosed by real-time PCR in 285 cases, including 105 natural varicella cases and 180 BV cases. VZV DNA was detected in 250 (87.8%) of the 285 cases by direct-LAMP. The presence and duration of fever, number of skin eruptions, and VZV DNA load were significantly lower in BV than natural varicella. The sensitivity of direct-LAMP for the diagnosis of varicella and BV was 93.3% and 84.4%, respectively. ConclusionsDirect LAMP was considered to be useful for rapid diagnosis of BV as it has several advantages such as low cost, ease and rapidity, as compared to real time PCR.

Scattering of the Fundamental Shear Guided Wave From a Surface-Breaking Crack in Plate-Like Structures.

Cracks in critical sections of steel structures pose a major safety concern in many industries. Existing high-frequency ultrasonic techniques offer high detection sensitivity to cracks but have poor inspection volume coverage, limiting their practical use for monitoring large areas of structures. Low-frequency guided waves have relatively high inspection area coverage and are currently used in pipeline monitoring for corrosion defects but face challenges in detecting critical cracks that often cause over an order of magnitude lower cross-sectional area loss. A study of scattering from small cracks in a thin-walled (<12 mm) section with an incident plane SH0 guided wave at higher frequencies but remaining below the SH1 cutoff is presented here using quasi-static approximations, the aim being to explore the possibility of using this regime for crack growth monitoring applications. A 3-D solution was developed using dimensional analysis, which showed that the SH0 reflection ratio is proportional to frequency to the power 1.5, to the effective crack size cubed, and is inversely proportional to the plate thickness and to the square root of the distance from the crack to the receiving sensor. Finite element analysis was used to validate these power coefficients and to calculate the proportionality constant. The results show that a higher inspection frequency offers improved sensitivity, but the validity of the results here is limited to the SH1 cutoff frequency. The predicted 3-D solution was validated by measurements on a pipe with a progressively grown notch.

System of rice intensification (SRI): An innovative and remunerative method of rice cultivation in Tripura, India

System of rice intensification (SRI) has been gaining momentum over the years in Tripura, one of the eastern states of India. To meet the growing rice demand, a rapid increase in paddy production is needed. Considering the growing importance of System of Rice Intensification (SRI) in the state, the need for such a study was felt and accordingly the present study was conducted in Sepahijala district of Tripura on the basis of highest area coverage under SRI among all districts of the State. SRI offers an interesting alternative to improve rice productivity. The present study was carried out to examine the comparative economics of SRI and conventional methods of rice cultivation in Tripura, India during the year 2016-17. For the study 120 sample farmers were selected by using multistage random sampling. The cost concepts were used are Cost A, Cost B and Cost C. This paper has compared the economics of SRI and the conventional methods of rice cultivation. It has shown that gross return and net return were much higher for SRI (Rs. 129000.50), (Rs. 67050.50) than conventional (Rs. 78444.00), (Rs. 27168.00), respectively. Similarly, the return over cost was higher for SRI (2.08) than conventional (1.52) methods. The present study concludes that SRI has a tremendous potential to increase the production of rice. Moreover, adoption of this technique by the farmers would give them higher yields which in turn will help them to earn more and improve their socio-economic situation. It has proved to serve as an alternative method for rice cultivation.

Estimation of Winter Wheat Residue Coverage Using Optical and SAR Remote Sensing Images

As an important part of the farmland ecosystem, crop residues provide a barrier against water erosion, and improve soil quality. Timely and accurate estimation of crop residue coverage (CRC) on a regional scale is essential for understanding the condition of ecosystems and the interactions with the surrounding environment. Satellite remote sensing is an effective way of regional CRC estimation. Both optical remote sensing and microwave remote sensing are common means of CRC estimation. However, CRC estimation based on optical imagery has the shortcomings of signal saturation in high coverage areas and susceptibility to weather conditions, while CRC estimation using microwave imagery is easily influenced by soil moisture and crop types. Synergistic use of optical and microwave remote sensing information may have the potential to improve estimation accuracy. Therefore, the objectives of this study were to: (i) Analyze the correlation between field measured CRC and satellite derived variables based on Sentinel-1 and Sentinel-2, (ii) investigate the relationship of CRC with new indices (OCRI-RPs) which combine optical crop residues indices (OCRIs) and radar parameters (RPs), and (iii) to estimate CRC in Yucheng County based on OCRI-RPs by optimal subset regression. The correlations between field measured CRC and satellite derived variables were evaluated by coefficient of determination (R2) and root mean square error (RMSE). The results showed that the normalized difference tillage index (NDTI) and radar indices 2 (RI2) had relatively higher correlations with field measured CRC in OCRIs and RPs (R2 = 0.570, RMSE = 6.560% and R2 = 0.430, RMSE = 7.052%, respectively). Combining OCRIs with RPs by multiplying each OCRI with each RP could significantly improve the ability of indices to estimate CRC, as NDTI × RI2 had the highest R2 value of 0.738 and lowest RMSE value of 5.140%. The optimal model for CRC estimation by optimal subset regression was constructed by NDI71 × σ V V 0 and NDTI × σ V H 0 , with a R2 value of 0.770 and a RMSE value of 4.846%, which had a great improvement when compared with the best results in OCRIs and RPs. The results demonstrated that the combination of optical remote sensing information and microwave remote sensing information could improve the accuracy of CRC estimation.

GIS-multicriteria evaluation using AHP for landslide susceptibility mapping in Oum Er Rbia high basin (Morocco)

BackgroundHigh basin of Oum Er Rbia River, which is located in Middle Atlas Mountain region, is prone to landslide problems due to the geological features combined with the climate change and human activities. The present work including inventory mapping was conducted to establish landslide susceptibility map using GIS-based spatial multicriteria approach. Eight landslide-related factors, including land cover, lithology, distance to road, distance to fault, distance to drainage network, elevation, aspect and slope gradient, were selected for the present assessment. Weight for each factor is assigned using Analytic Hierarchy Process (AHP) depending on its influence on the landslide occurrence. The landslide susceptibility map was derived using weighted overlay method and categorized into five susceptible classes namely, very low (VL), low (L), moderate (M), high (H).ResultThe results revealed that 30.16% of the study area is at very low risk, 12.66% at low risk, 25.75% of moderate risk, 22.59% of high risk and 9.11% of very high risk area coverage. The very high landslide vulnerability zones are more common within the river valleys on steep side slopes. Most landslides also involve rocks belonging to the Triassic weathered marl and clay-rich formation. Moreover, human activities namely the construction and the expansion of agricultural lands into forests intervene in inducing landslides through altering the slope stability along the river banks. Lastly, effectiveness of these results was checked by computing the area under ROC curve (AUC) that showed a satisfactory result of 76.7%.ConclusionsThe landslide susceptibility map of the Oum Er Rbia high basin provides valuable information about present and future landslides, which makes it viable. Such map may be helpful for planners and decision makers for land-use planning and slope management.