3D Simulation with virtual stereo rig for optimizing centrifugal fertilizer spreading

Stereovision can be used to characterize of the fertilizer centrifugal spreading process and to control the spreading fertilizer distribution pattern on the ground reference. Fertilizer grains, however, resemble each other and the grain images contain little information on texture. Therefore, the accuracy of stereo matching algorithms in literature cannot be used as a reference for stereo images of fertilizer grains. In order to evaluate stereo matching algorithms applied to images of grains a generator of synthetic stereo particle images is presented in this paper. The particle stereo image generator consists of two main parts: the particle 3D position generator and the virtual stereo rig. The particle 3D position generator uses a simple ballistic flight model and the disc characteristics to simulate the ejection and the displacement of grains. The virtual stereo rig simUlates the stereo acquisition system and generates stereo images, a disparity map and an occlusion map. The results are satisfying and present an accurate reference to evaluate stereo particles matching algorithms

Farm and farmer capital foster adoption of improved quality agrochemical inputs in the cotton-wheat zone of the Punjab, Pakistan

Adoption of yield-enhancing agricultural inputs fosters agricultural intensification in low-income countries. In Pakistan, initial adoption of agrochemicals is already widespread; the low quality of much of the inputs contributes to severe health, environmental and enduring pest problems, however. While the positive influence of farm capital and farmer capital on initial adoption is well documented, the adoption of improved quality inputs is little researched. We reduce the knowledge gap investigating smallholder adoption of improved quality agrochemical inputs in the Punjab, Pakistan. Using multi-stage random sampling, a pre-tested and piloted farming household survey was administered to smallholder farming households from 18 villages across three districts of the cotton-wheat zone (N=275). Ordered probit models show that several farming and farm capital variables (cotton crop area, farm machinery, no-tillage farming, adoption in the neighbourhood) as well as several farmer capital variables (age, education, off-farm income, agricultural extension services, source of agricultural credit) influence adoption of improved quality agrochemical inputs. Of these variables, an intensification of agricultural extension service visits appears as the most promising policy option. From a fundamental science point of view, our results provide, for the first time, evidence that adoption of improved quality agrochemical inputs is influenced principally by the same variables as initial adoption

The role of crop protection products of multinational brands for agricultural sustainability in the cotton-growing zone in Pakistan

Despite the use of Bt (Bacillus thuringiensis) cotton in Pakistan, the country is still far behind in farm harvest per unit compared to other cotton-producing countries such as China and Turkey. Cotton is a pest-sensitive crop, and inappropriate crop protection products contribute to lower agricultural sustainability. This issue attracts additional attention in developing countries such as Pakistan, where generic formulation/sub-standard crop protection products are easily and abundantly available. However, the impact of the application of crop protection products of multinational brands in contrast to generic formulation/sub-standard crop protection products on total farm revenue is explicitly not documented. We employ a stochastic frontier production framework using a survey of smallholder farming households in the cotton-growing zone in Pakistan (N=266). The estimates of stochastic frontier production models show a positive relationship between the use of crop protection products of multinational brands and total farm revenue. The estimates of technical inefficiency models show that specialisation and regional dummy, among others, emerge as the key to determining the smallholders’ technical inefficiency. To get higher farm revenue and technical efficiency, we propose the agricultural policy makers of Pakistan to explicitly focus on the quality of crop protection products. Moreover, agricultural policy makers are advised to revisit the cropping system in the study area. This revisit may positively contribute to agricultural sustainability

The Covariant W_3 Action

Starting from SL(3,R) Chern-Simons theory we derive the covariant action for W_3 gravity.Comment: 14 page

A Survey of Routing Issues and Associated Protocols in Underwater Wireless Sensor Networks

Underwater Wireless Sensor Network is newly emerging wireless technology in which small size sensors with limited energy, limited memory and bandwidth are deployed in deep sea water and various monitoring operation like tactical surveillance, environmental monitoring and data collection are performed through these tiny sensor. Underwater Wireless Sensor Network is used for exploration of underwater resources, oceanographic data collection, flood or disaster prevention, tactical surveillance system and unmanned underwater vehicles. Sensor node consist of small memory, central processing unit and antenna. Underwater network is much different from terrestrial sensor network as radio waves cannot be used in Underwater Wireless Sensor Network. Acoustic channels are used for communication in deep sea water. Acoustic Signals carries with itself many limitation. Such as Limited bandwidth, higher end to end delay, network path loss, higher propagation delay and dynamic topology. Usually these limitation results in higher energy consumption with less number of packets delivered. The main aim now a days is to operate sensor node having smaller battery for a longer time in network. This survey has discussed the state of the art Localization based and Localization free routing protocols. Routing associated issues in the area of Underwater Wireless Sensor Network has also been discussed

Diagnostic TCD for intracranial stenosis in acute stroke patients: experience from a tertiary care stroke center in Karachi, Pakistan.

Background: Stroke is a common cause of morbidity and mortality around the world. Intracranial large artery atherosclerosis (ICAD) is a frequent etiology of stroke in the South Asian population. There is a need for widely available screening tools to identify patients that are at high risk of stroke due to ICAD for aggressive risk management. This study describes the experience of using the transcranial Doppler (TCD) as a screening tool for this purpose at a tertiary care hospital in a developing country. Methods: 86 Patients admitted with stroke due to ICAD underwent TCD for six arteries (Right and left middle cerebral arteries, right and left anterior cerebral arteries, right and left posterior cerebral arteries) in addition to the magnetic resonance angiography (MRA) that is done routinely at the stroke center. Arteries were labeled with either50% stenosis by TCD using two separate criteria. These findings were compared with those from the MRA which was used as the gold standard. The proportion of patients that had complete exams (all six arteries insonated by TCD) was reported. The success rate of each TCD criteria in detecting arteries with \u3e50% stenosis was also calculated. Results: There was an attempt to visualize 516 arteries (86 patients with 6 arteries each) of which 375 (72.7%) were successfully insonated. 38 of the 86 (55.8%) patients had complete examinations. MRA reported 43 (8.3%) arteries as stenosed \u3e50%. The TCD did not categorize any artery as stenosed using either criterion and hence failed to classify any stenosed artery correctly. The positive predictive and sensitivity was 0 for this study and the negative predictive value was 93.3%. Conclusions: This study indicates the poor sensitivity of TCD to be a reliable screening tool for the presence of ICAD in the South Asian population in a real life clinical setting