Perturb and Observe Maximum Power Point Tracking for Photovoltaic Cell

Maximum power point tracking (MPPT) techniques are used in photovoltaic (PV) systems to maximize the PV array output power by tracking continuously the maximum power point (MPP) which depends on panel’s temperature and on irradiance conditions. The issue of MPPT has been addressed in different ways in the literature but, especially for low-cost implementations, the perturb and observe (P&O) maximum power point tracking algorithm is the most commonly used method due to its ease of implementation. A drawback of P&O is that, at steady state, the operating point oscillates around the MPP giving rise to the waste of some amount of available energy; moreover, it is well known that the P&O algorithm can be confused during those time intervals characterized by rapidly changing atmospheric conditions. In order to limit the negative effects associated to the above drawbacks, the P&O MPPT parameters must be customized to the dynamic behavior of the specific converter adopted. A theoretical analysis allowing the optimal choice of such parameters is also carried out. In this paper MATLAB-based M file programming scheme suitable for monitoring the I-V and P-V characteristics of a PV array under a nonuniform insolation due to partial shading condition for different configuration (modules in series parallel) of solar PV. It can also be used for developing and evaluating new maximum power point tracking techniques, especially for shaded conditions. Implementation of a novel MPPT technique has been developed using P&O algorithm has been done using MATLAB-based M file programming scheme without applying shading effect to solar array. Keywords: Maximum power point (MPP), maximum power point tracking (MPPT), perturb and observe (P&O), photovoltaic (PV

Study and Implementation of Cryptographic Algorithms

Cryptography has a long and fascinating history. Over the centuries, an elaborate set of protocols and mechanisms has been created to deal with information security issues when the information is conveyed by physical documents. Often the objectives of information security cannot solely be achieved through mathematical algorithms and protocols alone, but require procedural techniques and abidance of laws to achieve the desired result. For example, privacy of letters is provided by sealed envelopes delivered by an accepted mail service. The physical security of the envelope is, for practical necessity, limited and so laws are enacted which make it a criminal offense to open mail for which one is not authorized. It is sometimes the case that security is achieved not through the information itself but through the physical document recording it. For example, paper currency requires special inks and material to prevent counterfeiting

MANET Congestion Control Mechanism - Challenges and Survey

The transport layer plays a crucial role in the Mobile Adhoc Network (MANET) protocol stack by controlling traffic flow, managing congestion, and enabling end-to-end delivery. With the help of congestion control mechanisms, numerous protocols are formed to enhance MANET performance. This paper focuses on a thorough analysis of the challenges the MANET protocol stack is facing as a result of congestion control issues such high overload, long delays, and increased packet loss. Finally, note that in order to increase MANET performance, research needs to concentrate on specific congestion control mechanisms

Formulation Development and Evaluation of Bilayer Tablet for Effective Treatment of Gastric Ulcer

The present study was aimed at developing Gastro retentive bilayer drug delivery systems containing esomeprazole and clarithromycin for the treatment of H. pylori induced gastric ulcer to minimize the side effect, improve the prolongation of action, to reduce the frequency of drug administration. The tablet is characterized by immediate release layer of esomeprazole and Gastroretentive layer of clarithromycin. The formulation containing Gastroretentive layer was designed using HPMC K 15, HPMC K4 and PVP K30 as floating agents, sodium bicarbonate and citric acid as gas-generating agent. Crospovidone, sodium starch glycolate and croscarmellose sodium was used as superdisintegrant for the preparation of immediate release layer. The prepared Gastroretentive layer was evaluated for their precompression parameters, physical characteristics like hardness, friability, uniformity of weight, uniformity of drug content, swelling index, In-vitro floating studies and In-vitro drug release. The release of the esomeprazole from the immediate release layer was found to be 89.98 % in 15minutes. The release of clarithromycin for the sustained release floating layer was found to be 98.89±0.47% in 12 hours. The data obtained from In-vitro release were fitted into the various kinetic models (Zero Order, Higuchi, First Order and Korsmeyer–Peppas Model). Keywords: Esomeprazole, Clarithromycin, Bilayer floating tab, Crospovidone, Superdisintegran

Effect of ondansetron on sensory level produced by intrathecal bupivacaine

Background: For spinal anesthesia there are drugs which can increase the level and quality of analgesia. Any drug which decreases sensory block level in spinal anesthesia is of great concern as it may need analgesic, sedative, supplement or even conversion to general anesthesia. Ondansetron is one such drug which has been reported to decrease the height of sensory block achieved after subarachnoid administration of bupivacaine. In this prospective observational study, we studied the effect of administration of ondansetron on the level of the sensory block achieved after subarachnoid blockade.Methods: In Group II, 4 mg ondansetron was given and 15 mins before giving spinal anesthesia Group II against control group receiving 2 ml saline intravenous (Group I). 15 mins before giving spinal anesthesia. Both groups received 3.5 ml of bupivacaine heavy was given intrathecally. Sensory and motor block was assessed 5, 15, and 30 mins. We analyzed both highest spinal block level achieved and time to regress to L1 level.Results: We found that in Group II both highest level of sensory block (T6 by median method) duration to regress to L1 level (1.43±0.22 hrs) was lesser as compared to group I and Group III T4 by median method and time to regress from T6 to L1 Group I 2.03±0.06 hrs Group III 1.84±0.27 hrs. Motor block did not differ between groups.Conclusions: We concluded that probably ondansetron was responsible for lower spinal block level and early recovery from spinal anesthesia after intrathecal bupivacaine and should not be given empirically for nausea and vomiting

MANET Hidden and Exposed Terminal - Challenges and Survey

Mobile Adhoc Network (MANET)is a self organized wireless Network which was created to communicate among  the nodes without support of the any Infrastructure. While transmission of the packets between the nodes, many challenges the every nodes faces. One of the Major challenges is Hidden and Exposed nodes issues in the MANET. This causes the packet drop or packet failure while the transmitting the packets. Also which  reflects in degrades the throughput of the MANET and performance of the MANET nodes when the heavy traffic ,retransmission of the dropped packets delayed the communication. This article discussed about hidden and Exposed terminal problem and challenges in MANET and also dissimilar survey in MANET