maximum point
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2021 ◽  
Vol 2021 ◽  
pp. 1-9
Author(s):  
Yong Wang ◽  
Hongjian Ni ◽  
Ruihe Wang ◽  
Peng Lei ◽  
Bin Huang ◽  
...  

Pulsed jet significantly affects the pore pressure of deep formation and then affects the mechanical ROP. In this paper, the effect of jet pulsation on deep pore pressure in the formation is studied by the finite element method. Under the pulsed jet, the maximum relative negative pressure is along the wellbore axis, and the farther it is to the borehole axis, the smaller the relative negative pressure is. With the increase of pulse frequency, the relative negative pressure increases and the maximum point of relative negative pressure moves upward. The optimum pulse frequency is from 50 Hz to 500 Hz. There is a linear relationship between pulse amplitude and relative negative pressure.


Energies ◽  
2021 ◽  
Vol 15 (1) ◽  
pp. 26
Author(s):  
Marcin Szczepaniak ◽  
Paweł Otręba ◽  
Piotr Otręba ◽  
Tomasz Sikora

The use of solar panels in low-power applications is an increasingly developing topic. Various methods are currently used to obtain the highest possible solar panel power generation efficiency. The methods of determining the maximum power point (MPP) and its tracking are under constant development, resulting in the creation of new algorithms to accelerate the operational efficiency while maintaining good parameters. Typically, these methods are only used in high-power photovoltaic installations. Due to the problems resulting from the adjustment to MPP working conditions for low-power solar panels used to charge a Li-Ion battery, an attempt was made to check the feasibility of operating control based on a Pulse Width Modulation (PWM) method and a Maximum Power Point Tracking (MPPT) algorithm like the one used in high-power solar systems also for low-power systems. The article presents adaptation of PWM and MPPT methods for small chargers, including the stages of modelling a solar charger and the results of a computer simulation of the charger operation. The stages of building a real, physical device are also presented. From the analysis of the test results of the constructed charger in real- and laboratory conditions with the use of a device imitating sunlight, the so-called solar box, and comparisons with computer simulations show that the assumed goal was achieved. The results obtained with the PWM method were compared with the MPPT method. The optimization of the device operation parameters and improvement of the algorithms used in the MPPT method resulted in better optimalization of maximum point tracking, improving the efficiency of energy storage from solar cells.


2021 ◽  
Vol 13 (2) ◽  
pp. 98-108
Author(s):  
Indah Soesanti ◽  
Ramadoni Syahputra

A fuzzy control system has been widely used in various problem solving. Its performance can be optimized using particle swarm optimization (PSO). This performance can be proven by applying it to the maximum power point tracking (MPPT) control strategy on solar photovoltaic systems. Solar photovoltaic power generation systems are increasingly popular because they are clean and renewable energy sources. The power generated by solar photovoltaic is strongly influenced by solar irradiation and the load carried. In order to obtain maximum power output, an MPPT control strategy is needed. An MPPT control strategy based on fuzzy and PSO hybrid control systems is proposed in this research. The fuzzy-PSO method selects and produces the optimal duty cycle for the boost dc-dc converter in a solar photovoltaic system. Variable duty cycle due to solar irradiation and load changes can be conditioned by the fuzzy-PSO-based MPPT method to extract maximum power. The research results show that the fuzzy-PSO method can control the solar photovoltaic output voltage through a dc-dc converter to produce maximum power at various solar irradiations. Test result by applying a resistive load produces output power at the maximum point. The best result is obtained in the 100 Ohm load test: the response time of 0.0818 seconds and excellent robustness.


2021 ◽  
Vol 5 (1) ◽  
pp. 163
Author(s):  
Romaden Marbun ◽  
Rea Ariyanti ◽  
Vincensia Dea

ABSTRAKRekam medis merupakan bagian dari arsip yang menggambarkan segala aktivitas sebuah fasilitas pelayanan kesehatan dalam kurun waktu tertentu. Rekam Medis ialah berkas yang berisikan catatan dan dokumen tentang identitas pasien, pemeriksaan, pengobatan, tindakan, dan pelayanan lain yang telah diberikan kepada pasien. Rekam medis ini memiliki fungsi penting bagi pasien dan juga dokter. Oleh karena itu pengisian rekam medis ini harus lengkap dan tidak boleh ditunda pengisiannya baik bagi pasien ataupun tenaga kesehatan. Namun, banyak masyarakat yang belum mengetahui fungsi penting dari melengkapi rekam medis dan keterbukaan informasi pribadinya yang harus diberikan kepada fasilitas pelayanan kesehatan bahkan tenaga kesehatan yang merawatnya dalam menunjang mutu informasi pada rekam medis tersebut. Tujuan kegiatan ini adalah meningkatkan pengetahuan masyarakat khususnya RT 09 Kelurahan Bandulan Kota Malang tentang pentingnya rekam medis bagi masyarakat yang berobat di fasilitas pelayanan kesehatan. Metode penyuluhan dilakukan secara tidak langsung atau dalam jaringan (daring) dengan berkoordinasi via online grup whatsapp selama 3 kali pertemuan serta dikirimkan materi presentasi serta video pembelajaran. Masyarakat yang terlibat sebanyak 34 orang. Tahap evaluasi dilakukan melalui google form. Hasil kegiatan diperoleh peningkatan pengetahuan masyarakat dari rata-rata 37,53 menjadi 79,06 dengan point maksimal 100. Kegiatan berjalan dengan baik dan perlu adanya monitoring lebih lanjut. Kata kunci: pengetahuan; masyarakat; rekam medis; fasilitas pelayanan kesehatan. ABSTRACTThe medical record is part of the archive that describes all the activities of a health care facility within a certain period of time. Medical Record is a file that contains records and documents about the patient's identity, examination, treatment, action, and other services that have been provided to the patient. This medical record has an important function for patients as well as doctors. Therefore, the filling of this medical record must be complete and the filling should not be delayed either for the patient or the health worker. However, many people do not know the important function of completing medical records and the disclosure of personal information that must be provided to health care facilities and even health workers who take care of them in supporting the quality of information in the medical record. The purpose of this activity is to increase public knowledge, especially RT 09 RW 05 Kelurahan Bandulan Malang City about the importance of medical records for people who seek treatment at health service facilities. The counseling method is carried out indirectly or online by coordinating via online WhatsApp groups for 3 meetings and sending presentation materials and learning videos. There were 34 people involved. The evaluation stage is carried out through a google form. The results of the activity obtained an increase in public knowledge from an average of 37.53 to 79.06 with a maximum point of 100. The activity went well and needed further monitoring. Keywords: knowledge; public; medical records; health service facilities.


2021 ◽  
Vol 11 (12) ◽  
pp. 3223-3236
Author(s):  
C. Karuppasamy ◽  
S. Venkatanarayanan

In order to gather, transmit, and develop input from the patients for monitoring their health condition through smart devices or devices which use embedded systems, such as processors and transducers and equipment for communication in the healthcare system, the Internet of Medical Things (IoMT) maintains a huge network infrastructure. These devices therefore comprise of a powerful, scalable, lightweight storage knot, which requires power and batteries to run from a practical standpoint. The above shows that the energy collection plays a significant part in the enhancement of IoMT devices’ efficiency and lifespan for its application in healthcare systems. Moreover, in view of the energy acquisition from the operational environment, energy collection is required to make the IoMT devices network more ecologically sustainable. In large solar PV generating systems, partly shading situations usually develop, causing system losses. Thus, in power-voltage curves characteristic of solar systems, the appearance of several peak levels is conceivable. These kinds of problems can be handled by using new multilayer link inverter monitoring techniques. A Maximum Point Tracking Scheme (MPPT) is being suggested for self-proposed Internet of Medical Things for the purpose of optimizing harvesting of solar power on entire PV chain with the usage of RGWO (Robust Wolf Optimization) dependent PI with PWM. The mistaken PV error might create inconsistent power supply to the 7-level H-bridge inverter linked to a grid. The modulation compensation is included in the control system in order to stabilize the grid power. The suggested technique is applied to a 7-level inverter under partial shade conditions. The multi-level modular H-bridge inverter is used for the grid-linked PV system. In addition to a DC link across all H-bridges, a short PV panel string is used for feeding each phase of n H-bridge converters which is connected in series. For pulse switching inverters, the usage of RGWO-based PI with PWM is used. The PWM is used. Then L filters used to reduce the switch harmonics found in the grid are used to link the Cascade multilevel inverter with the grid. A seven-level threephase inverter with three H-bridges allows the individual MPPT control need. The harvester is under direct sunlight and sometimes overcast circumstances realistically tested outside. The wearable IoMT sensor node uses a mean power of 20, 23 mW in a wake-up mode for one hour, and the node’s service life is 28 hours. The performance analysis is finally performed and MATLAB/SIMULINK simulation is performed.


2021 ◽  
Vol 2131 (3) ◽  
pp. 032001
Author(s):  
I V Pavlov ◽  
N V Neumerzhitskaia ◽  
S I Uglich ◽  
T A Volosatova

Abstract The main result of this paper is the proof of the strict concavity of some function of integral form depending on three random variables, which we call priorities. This function is an objective function in the so-called model with priorities, in which the arbiter, following expert opinions, distributes funds among the enterprises and institutions under his jurisdiction. This result implies an important corollary about the existence and uniqueness of a local maximum point (which is also a global maximum point) of the objective function. This is a significant generalization of the corresponding result of N.V. Neumezhitskaia, S.I. Uglich and T.A. Volosatova, published in December 2020.


Author(s):  
Benlaria Ismail ◽  
Belhadj Mohammed ◽  
Othmane Abdelkhalek ◽  
Sabouni Elhadj

<p>Photovoltaic (PV) systems can be made more efficient by forcing the PV panel to operate at its maximum point power due to the electrical properties of photovoltaic generators, which are substantially non-linear (MPP). This study examines the effectiveness of using a combination of parabolic concentrator Bi-reflector and heat exchanger as a cooling system on the performance of photovoltaic generators to get a photovoltaic/thermal (PV/T) system, and their effect on the direct current (DCDC) converter using matrix laboratory (MATLAB) simulink. The experimental tests were carried out under various temperature values and sun irradiation. The results demonstrated that the use of parabolic Bi-reflectors, to further illumine te the panels, and the use of the cooling system to absorb excess heat to get heat water, could increase and enhances performances of the photovoltaic generator.</p>


2021 ◽  
Vol 54 (2E) ◽  
pp. 150-163
Author(s):  
Nguyen Kim Dung

The position of a maximum point of a function depends on its coefficients and order. The maximum horizontal gradient method is a popular method that greatly contributes to the detection of maximum points and approximation of geological structures edges. By adopting a mathematical logic, Blakely and Simpson established a quadratic function based on the characteristic of three points of a straight line in the fundamental directions. However, for potential field data like gravity and magnetic data, the coefficients of a quadratic function in each direction are not only dependent on the values of three points on a straight line, but also, they depend on the values of the surrounding points. This article proposes an algorithm which can detect maximum points more effectively in order to delineate geological structures boundaries from potential field data. The proposed algorithm uses a 3×3 neighborhood data grid to establish a two-variables function and to determine its coefficients by applying the Gaussian elimination method. After the two-variables function has been established, the algorithm estimates any extreme points and their positions from a set of four single-variable functions which correspond to the horizontal, vertical and the two diagonal directions by the cases x = 0, y = 0, y = -x and y = x of the main function. Finally, the conditions to detect the maximum point from the extreme points are defined. The validity of the algorithm was demonstrated on synthetic datasets generated by two different model structures. A real data application of the method has also been realized by estimating the geological boundaries by gravity data in the Vietnam’s continental shelf. The results obtained from the synthetic applications of the algorithm proved that it can determine more maximum points as compared to Blakely and Simpson method, and as a result, in all the test cases, it has drawn the real boundaries of the model structures more accurately. The application results of the method on real data revealed new boundary delineations in the research area, interpreted to be faults or fractures which lies between deep trench in the East Vietnam Sea.


2021 ◽  
pp. 030089162110598
Author(s):  
Donghyun Kim ◽  
Yongkan Ki ◽  
Wontaek Kim ◽  
Dahl Park ◽  
Jihyeon Joo ◽  
...  

Objective: To identify risk factors of primary site necrosis (PSN) after definitive concurrent chemoradiation therapy (CCRT) in patients with nonoral cavity head and neck cancer (HNC). Methods: We retrospectively reviewed the records of 256 patients treated with CCRT for HNC during 2010–2018. Patient-related (age, sex, history of smoking, hypertension, diabetes mellitus, serum hemoglobin and albumin), tumor-related (tumor site, American Joint Committee on Cancer stage), and treatment-related (induction chemotherapy, maximum point dose and mean dose of planning target volume [PTV] of primary site, absolute volumes of the PTV receiving >50–75 Gy [V50–V75]) variables were analyzed. Critical dosimetric parameters of PSN were identified using receiver operating characteristic (ROC) curve analysis. Univariate and multivariate Cox regression analyses were used to select the significant variables for PSN development. Results: After median follow-up of 44 months (range, 5–127), 7 patients (2.7%) developed PSN with a median time to event of 10 months (range, 3–12). V70 ⩾79.8 mL was the most critical dosimetric parameter for PSN (area under the ROC curve 0.873, sensitivity 0.857, specificity 0.747). In univariate analyses, pretreatment serum hemoglobin <11.0 g/dL and V70 ⩾79.8 mL were significantly associated with higher risk of PSN occurrence. V70 ⩾79.8 mL (hazard ratio 5.960, 95% confidence interval 1.289–27.548; p = 0.022) remained significant predictors of PSN in multivariate analyses. Conclusions: V70 ⩾79.8 mL is significantly related to the risk of developing PSN. These findings offer valuable clues for clinicians to minimize PSN incidence in HNC treated with curative CCRT.


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