A novel combined approach for gas compressors surge suppression based on robust adaptive control and backstepping

Malek Ghanavati,Karim Salahshoor,Mohammad Reza Jahed Motlagh,Amin Ramazani,Ali Moarefianpour 대한기계학회 2018 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.32 No.2

Nowadays, there is a great interest in using active control methods to increase the compressor working range. The advantage of this controlling method is that the performance point can be located in the vicinity of maximum pressure and efficiency. However, most of the existing controllers require an awareness of compressor characteristic, disturbance upper bound, throttle gain, and throttle valve feature; this is why they are limited in engineering applications. In order to overcome the weakness of the existing controllers, this research employs a novel combined controlling method based on robust adaptive control, which is designed using backstepping technique because the compressor behavior is nonlinear. The increased efficiency and improved operational area for the compressor are provided by this controller without requiring any knowledge or information regarding the compressor characteristic, disturbance upper bound, throttle gain, and throttle valve feature. The adaptive controller has been used to compensate for uncertainties of the compressor characteristic and throttle valve as well as the un-modeled dynamics. Also, the controller robustness is a barrier against the time-varying disturbances in flow and pressure applied to the system. Finally, simulation results showed that the designed controller, in addition to assure the system stability, developed the compressor working range, and the convergence of system states was achieved after applying disturbance in flow and pressure.

The influence of substrate topography and biomaterial substance on skin wound healing

Zeinab Ghanavati,Niloofar Neisi,Vahid Bayati,Manoochehr Makvandi 대한해부학회 2015 Anatomy & Cell Biology Vol.48 No.4

Tissue engineering is a new field of which the main purpose is to regenerate and repair the damaged tissues. Scaffolds serve as three dimensional matrices for neo-organogenesis and their substance can be biologic or synthetic. Natural polymers have good interactions with the cells and synthetic biomaterials are also highly useful in biomedical application because of their biocompatible properties. In addition to scaffold substance, surface properties of biomaterials have an important role in tissue engineering. In this study, we examined whether substrate substance is important for wound healing or its surface topography. Therefore, we fabricated two matrices, electrospun polycaprolactone (PCL) nanofibers and collagen/chitosan film, and implanted them to the same rat models. After 2 weeks, the sizes of healing wounds were measured and their cellular structures were evaluated by histochemistry and immunohistochemistry. Histological staining showed a good level of ellularization and epidermis-dermis formation in PCL implant while no determinable epithelium was observed after 2 weeks in collagen-chitosan graft. Immunohistochemical study demonstrated the highly expressed pancytokeratin in PCL graft while its expression was weak in underdeveloped epidermis of collagen-chitosan implantation. In conclusion, this study suggested that PCL nanofibers with high surface area had a more ideal property than natural collagen-chitosan film, therefore the structure and topography of a matrix seemed to be more important in wound healing than its material substance.

Monitoring Growth and Lipid Production of New Isolated Oleaginous Yeast Cryptococcus aerius UIMC65 on Glucose and Xylose Cultures

Hossein Ghanavati,Iraj Nahvi,Rasoul Roghanian 한국생물공학회 2014 Biotechnology and Bioprocess Engineering Vol.19 No.3

Process monitoring is one of the most importantfactors affecting production efficiency at industrial scalebioprocesses. In the present work, Flow-cytometric analysishas been employed to monitor and determine neutral lipidcell droplets, granularity and size of the cells of the newoleaginous yeast, Cryptococcus aerius UIMC65. It hasbeen shown that, differences of fluorescent intensity aswell as side and forward scatter light properties have closecorrelations with the differences in lipid production bythese yeast cells. The lipid content-related fluorescentintensity versus forward scatter parameter has been used tomonitor and compare different subpopulations during growthphases on both glucose and xylose in batch cultures. Flowcytometric results have revealed that the observed differencesin the proportion of each subpopulation were related to thespecific growth phase and lipid content of the cells. Thehighest lipid content and lipid productivity were attained at82.62%, 4.47 g/L (at 72 h) and 78.41%, 6.21 g/L (at 60 h)on glucose and xylose growth cultures, respectively. Thehighest biomass, lipid yield and biomass yield were foundto be 7.92 g/L (on glucose culture, at 60 h), 20.92% (onglucose culture, at 48 h) and 50.71% (on glucose culture,at 24 h), respectively.

Genetic diversity revealed by phytochemical and molecular analyses among and within eight Trigonella sp.

Mirzahosein-Tabrizi Maryam,Ghanavati Farangis,Azizinezhad Reza,Etminan Alireza 한국작물학회 2023 Journal of crop science and biotechnology Vol.26 No.3

Genetic diversity is a key factor for breeding programs and provides opportunities for developing superior varieties with preferred traits. Trigonella is a large genus of plants that is important in culinary terms and for the food industry. The present research aimed to study genetic diversity and population structure in a set of 90 accessions from eight diferent species of Trigonella sp. using 20 URP and SCoT primers. Also, fve amino acids and Trigonelline content were determined in the plants. The average marker index was 3.43 and 3.73 for SCoT and URP primers, respectively. NJ clustering was based on combined data and classifed all 90 accessions clearly, based on their species. AMOVA revealed that the main part (68%) of total variation occurring within species and T. monantha was the most diverse population among all species. According to the phytochemical, there were signifcant diferences between all species in terms of trigonelline content and the amounts of amino acids. High levels of genetic diversity were identifed among and within the eight species which can be considered for breeding purposes. Furthermore, URP and SCoT were found useful markers for the analysis of genetic diversity and population structures in Trigonella sp. Meanwhile, Trigonella foenum-graecum showed the highest Trigonelline content. As a matter of the health benefts provided by this alkaloid, T. foenum-graecum can be used not only for medicinal purposes but also as a useful vegetable and food ingredient.

The effect of the Iranian family approach-specific course (IrFASC) on obtaining consent from deceased organ donors’ families

Ehsan Radi,Matin Ghanavati,Batoul Khoundabi,Jamal Rahmani,Katayoun Nahafizadeh,Mahdi Shadnoush,Behrooz Broumand,Omid Ghobadi 대한이식학회 2022 Korean Journal of Transplantation Vol.36 No.4

Background: A family approach and obtaining consent from the families of potential brain-dead donors is the most important step of organ procurement in countries where an opt-in policy applies to organ donation. Health care staff’s communication skills and ability to have conversations about donation under circumstances of grief and emotion play a crucial role in families’ decision-making process and, consequently, the consent rate. Methods: A new training course, called the Iranian family approach-specific course (IrFASC), was designed with the aim of improving interviewers’ skills and knowledge, sharing experiences, and increasing coordinators’ confidence. The IrFASC was administered to three groups of coordinators. The family consent rate of participants in the same intervals (12 months for group 1, 6 months for group 2, and 3 months for group 3) was measured before and after the training course. The Wilcoxon signed-rank test was used to make comparisons. Results: The family consent rate was significantly different for all participants before and after the training, increasing from 50.0% to 62.5% (P=0.037). Furthermore, sex (P=0.005), previous training (P=0.090), education (P=0.068), and duration of work as a coordinator (P=0.008) had significant effects on the difference in families’ consent rates before and after IrFASC. Conclusions: This study showed that the IrFASC training method could improve the success of coordinators in obtaining family consent.

The Impact of Job Stress and Job Satisfaction on Workforce Productivity in an Iranian Petrochemical Industry

Hoboubi, Naser,Choobineh, Alireza,Ghanavati, Fatemeh Kamari,Keshavarzi, Sareh,Hosseini, Ali Akbar Occupational Safety and Health Research Institute 2017 Safety and health at work Vol.8 No.1

Background: Job stress and job satisfaction are important factors affecting workforce productivity. This study was carried out to investigate the job stress, job satisfaction, and workforce productivity levels, to examine the effects of job stress and job satisfaction on workforce productivity, and to identify factors associated with productivity decrement among employees of an Iranian petrochemical industry. Methods: In this study, 125 randomly selected employees of an Iranian petrochemical company participated. The data were collected using the demographic questionnaire, Osipow occupational stress questionnaire to investigate the level of job stress, Job Descriptive Index to examine job satisfaction, and Hersey and Goldsmith questionnaire to investigate productivity in the study population. Results: The levels of employees' perceived job stress and job satisfaction were moderate-high and moderate, respectively. Also, their productivity was evaluated as moderate. Although the relationship between job stress and productivity indices was not statistically significant, the positive correlation between job satisfaction and productivity indices was statistically significant. The regression modeling demonstrated that productivity was significantly associated with shift schedule, the second and the third dimensions of job stress (role insufficiency and role ambiguity), and the second dimension of job satisfaction (supervision). Conclusion: Corrective measures are necessary to improve the shift work system. "Role insufficiency" and "role ambiguity" should be improved and supervisor support must be increased to reduce job stress and increase job satisfaction and productivity.

Experimental study on the water inlet and outlet position of a solar collector reservoir for maximum efficiency

S. Khodadadi,A. Ghanavati,M. R. Assari,M. Hatami,D. D. Ganji 대한기계학회 2015 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.29 No.5

An experimental study is conducted on the heat transfer in the reservoir of a solar water-heater flat-plate solar collector to obtain itstemperature distribution. A total of 29 temperature sensors are placed inside the reservoir, and 2 sensors in the water inlet and outlet passages. The effect of the inlet and outlet positions on the temperature distribution inside the reservoir is studied to obtain the best locationfor the maximum temperature range. When the inlet position is II and the outlet position is B (Fig. 3(c)), the reservoir exhibits the bestperformance because of the high temperature range and areas inside it.

The Impact of Job Stress and Job Satisfaction on Workforce Productivity in an Iranian Petrochemical Industry

Naser Hoboubi,Alireza Choobineh,Fatemeh Kamari Ghanavati,Sareh Keshavarzi,Ali Akbar Hosseini 한국산업안전보건공단 산업안전보건연구원 2017 Safety and health at work Vol.8 No.1

Background: Job stress and job satisfaction are important factors affecting workforce productivity. This study was carried out to investigate the job stress, job satisfaction, and workforce productivity levels, to examine the effects of job stress and job satisfaction on workforce productivity, and to identify factors associated with productivity decrement among employees of an Iranian petrochemical industry. Methods: In this study, 125 randomly selected employees of an Iranian petrochemical company participated. The data were collected using the demographic questionnaire, Osipow occupational stress questionnaire to investigate the level of job stress, Job Descriptive Index to examine job satisfaction, and Hersey and Goldsmith questionnaire to investigate productivity in the study population. Results: The levels of employees’ perceived job stress and job satisfaction were moderate-high and moderate, respectively. Also, their productivity was evaluated as moderate. Although the relationship between job stress and productivity indices was not statistically significant, the positive correlation between job satisfaction and productivity indices was statistically significant. The regression modeling demonstrated that productivity was significantly associated with shift schedule, the second and the third dimensions of job stress (role insufficiency and role ambiguity), and the second dimension of job satisfaction (supervision). Conclusion: Corrective measures are necessary to improve the shift work system. “Role insufficiency” and “role ambiguity” should be improved and supervisor support must be increased to reduce job stress and increase job satisfaction and productivity.

Effects of counter torque and transposition (transfer) of installed implants timing on their integration in dog tibia

Mohammad Reza Karimi,Shima Fathi,Farzin Ghanavati 대한치과보철학회 2015 The Journal of Advanced Prosthodontics Vol.7 No.1

PURPOSE The purpose of this research was to evaluate the amount of reosseointegration after counter torquing (reverse torque) and transposing the installed implants at different times. MATERIALS AND METHODS This study was done on ten tibiae of five cross-bred dogs. At the first day one implant was installed in each tibia. After one week half of the implants were randomly counter torqued (1WCT) and the other half were explanted and reimplanted in a new juxtaposition site (transposed)(1WT). At the same time three new implants were installed in each dog, one of them was considered as one week control (1WC) and remaining two as 8 week groups (8WCT&8WT). After eight weeks the 1WCT and 1WT implants were loosened by counter torque and the quantity of needed force for liberation was measured with the digital device (BGI). At the same time one implant was installed in each dog as eight week control (8WC) and the same protocol was repeated for 8 week groups after another 8 weeks. RESULTS All implants were osseointegrated. Mean quantities of osseointegration in case groups indicated better amounts rather than control groups. CONCLUSION Counter torque or transposition of the installed implants one week or eight weeks after the implantation did lead to osseointegration.

Effects of counter torque and transposition (transfer) of installed implants timing on their integration in dog tibia

Karimi, Mohammad Reza,Fathi, Shima,Ghanavati, Farzin The Korean Academy of Prosthodonitics 2015 The Journal of Advanced Prosthodontics Vol.7 No.1

PURPOSE. The purpose of this research was to evaluate the amount of reosseointegration after counter torquing (reverse torque) and transposing the installed implants at different times. MATERIALS AND METHODS. This study was done on ten tibiae of five cross-bred dogs. At the first day one implant was installed in each tibia. After one week half of the implants were randomly counter torqued (1WCT) and the other half were explanted and reimplanted in a new juxtaposition site (transposed)(1WT). At the same time three new implants were installed in each dog, one of them was considered as one week control (1WC) and remaining two as 8 week groups (8WCT&8WT). After eight weeks the 1WCT and 1WT implants were loosened by counter torque and the quantity of needed force for liberation was measured with the digital device (BGI). At the same time one implant was installed in each dog as eight week control (8WC) and the same protocol was repeated for 8 week groups after another 8 weeks. RESULTS. All implants were osseointegrated. Mean quantities of osseointegration in case groups indicated better amounts rather than control groups. CONCLUSION. Counter torque or transposition of the installed implants one week or eight weeks after the implantation did lead to osseointegration.