Microstructural, hardening, and wear characteristics of surface re-melted AISI 410S stainless steel via fiber laser process

Behdad Nayebi,Hamidreza Najafi,Amirreza Farnia 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.10

AISI 410S ferritic stainless steel was surface melted via a continuous fiber laser at different scan rates. The microstructural characteristics, thickness, hardness, and tribological behavior of the laser melted (LSMed) surface were studied after different scan rates. The hardened layer thickness was inversely related to the scan rate. The thickness reduced from 146 μm at the scan rate of 15 mm.s -1 to 110 μm at the scan rate of 24 mm.s -1 . The microstructural studies revealed that the microstructure of the hardened layers mostly consisted of martensite. At the lowest scan rate, the martensite was in two forms of fine and coarse packets. The surface hardness enhanced with decreasing the scan rate. The maximum average hardness (330 HV) was obtained from the scan speed of 15 mm.s -1 . However, the most surface hardness scattering was observed in the sample treated by the lowest scan speed. The sample treated using the moderate scan rate (20 mm.s -1 ) demonstrated superior wear resistance due to its lowest coefficient of friction (COF) and weight loss. The reason for this behavior could be related to the appropriate melted thickness. Microstructural studies revealed that abrasive wear and adhesive wear were the dominant mechanisms in the worn surfaces.

Preemptive Use of Ketamine on Post Operative Pain of Appendectomy

Behdad, Akbar,Hosseinpour, Mehrdad,Khorasani, Parastoo The Korean Pain Society 2011 The Korean Journal of Pain Vol.24 No.3

Background: Although early reviews of clinical findings were mostly negative, there is still a widespread belief for the efficacy of preemptive analgesia among clinicians. In this study, we evaluated whether the preemptive use of ketamine decreases post operative pain in patients undergoing appendectomy. Methods: In double-blind, randomized clinical trials, 80 adult male patients undergoing an operation for acute appendicitis were studied. Patients were randomly assigned to two groups. In the operating room, patients in the ketamine group received 0.5 mg/kg of ketamine IV 10 minutes before the surgical incision. In the control group, 0.5 mg/kg of normal saline was injected. The pain intensity was assessed at time 0 (immediately after arousal) and 4, 12, and 24 hours postoperatively using the 10 points visual analogue scale (VAS). Results: Eighty patients (40 for both groups) were enrolled in this study. For all of the evaluated times, the VAS score was significantly lower in the ketamine group compared to the control. The interval time for the first analgesic request was $23.1{\pm}6.7$ minutes for the case group and $18.1{\pm}7.3$ minutes for the control (P = 0.02). The total number of pethidine injections in the first 24 hours postoperatively was $0.6{\pm}0.6$ for the case group and $2.0{\pm}0.8$ for the controls (P = 0.032). There were no drug side effects for the case group. Conclusions: A low dose of intravenously administered ketamine had a preemptive effect in reducing pain after appendectomy.

The Effects of Propofol and Isoflurane on Blood Glucose during Abdominal Hysterectomy in Diabetic Patients

Shekoufeh Behdad,Abulghasem Mortazavizadeh,Vida Ayatollahi,Zahra Khadiv,Saidhossein Khalilzadeh 대한당뇨병학회 2014 Diabetes and Metabolism Journal Vol.38 No.4

Background: Acute hyperglycemia in the perioperative period is associated with significantly increased complications. In few human studies the effects of propofol and inhalational anesthetic on the glucose metabolism were compared. In this study we evaluated the effect of propofol and isoflurane on blood glucose during abdominal hysterectomy in diabetic patients. Methods: After approval by the Ethical Committee and written informed consent, thirty 35 to 65 years old diabetic women underwent for elective abdominal hysterectomy under general anesthesia were studied in this randomized single blind clinical trial study. The plasma glucose was maintained at 100 to 180 mg/dL during the operation. Anesthesia protocol was similar in two groups except maintenance of anesthesia that was with infusion of propofol in the propofol group and with isoflurane in the isoflurane group. Blood glucose level and the rate of insulin intake during surgery compared between two groups. Results: Mean blood glucose before induction of anesthesia did not have significant difference between two groups, but 60 and 90 minutes after starting the operation blood glucose in the propofol group was significantly lower than isoflurane group. Also with using Repeated Measure test, two groups was significantly different according to blood glucose (P=0.045). Mean of administration of insulin during the surgery did not have significant difference between two groups by using repeated measure test and P=0.271. Also mean of bispectral index in different times during the surgery between two groups didn’t have significant difference (P=0.35 repeated measure test). Conclusion: Blood glucose increased during maintenance of anesthesia with isoflurane compared to propofol during the surgery.

Approximate Methods to Estimate Residual Drift Demands in Steel Structures with Viscous Dampers Designed by the DDBD Approach

Seyed Behdad Alehojjat,Masood Yakhchalian,Omid Bahar 한국강구조학회 2023 International Journal of Steel Structures Vol.23 No.3

Nowadays, using performance-based design procedures are widely applied by structural engineers. The direct displacement-based design (DDBD) approach is also one of the most efficient and popular procedures in these frameworks. This paper investigates the residual inter-story drift ratio (RIDR) demands in the mid-rise steel structures equipped with fluid viscous dampers (FVDs) designed by the modified DDBD approach. For this purpose, the capability of three approximate methods, i.e., the FEMA P-58, Erochko et al. and coefficients methods for estimating RIDR demands is studied. These methods have been proposed for moment-resisting frames (MRFs) without dampers. In order to evaluate the estimated RIDR demands in the approximate methods, three mid-rise steel MRFs with different velocity exponents for FVDs are designed according to the modified DDBD approach. Nonlinear time-history analyses are carried out by a set of spectrum-matched records at two seismic hazard levels including the designed earthquake (DE) and maximum considered earthquake (MCE). The results show that in most cases the Erochko et al. method overestimates the mean of maximum RIDRs at both the DE and MCE hazard levels. On the other hand, although the FEMA P-58 method overestimates the median of maximum RIDRs, when compared with the corresponding values obtained from analyses at the DE level, it underestimates the values at the MCE level. Also, the coefficients method is calibrated for the structures studied. Finally, a modified equation for a more precise estimation of RIDR demands is presented, by implementing the particle swarm optimization (PSO) algorithm.

Preemptive Use of Ketamine on Post Operative Pain of Appendectomy

( Akbar Behdad ),( Mehrdad Hosseinpour ),( Parastoo Khorasani ) 대한통증학회 2011 The Korean Journal of Pain Vol.24 No.3

Background: Although early reviews of clinical findings were mostly negative, there is still a widespread belief for the efficacy of preemptive analgesia among clinicians. In this study, we evaluated whether the preemptive use of ketamine decreases post operative pain in patients undergoing appendectomy. Methods: In double-blind, randomized clinical trials, 80 adult male patients undergoing an operation for acute appendicitis were studied. Patients were randomly assigned to two groups. In the operating room, patients in the ketamine group received 0.5 mg/kg of ketamine IV 10 minutes before the surgical incision. In the control group, 0.5 mg/kg of normal saline was injected. The pain intensity was assessed at time 0 (immediately after arousal) and 4, 12, and 24 hours postoperatively using the 10 points visual analogue scale (VAS). Results: Eighty patients (40 for both groups) were enrolled in this study. For all of the evaluated times, the VAS score was significantly lower in the ketamine group compared to the control. The interval time for the first analgesic request was 23.1 ± 6.7 minutes for the case group and 18.1 ± 7.3 minutes for the control (P = 0.02). The total number of pethidine injections in the first 24 hours postoperatively was 0.6 ± 0.6 for the case group and 2.0 ± 0.8 for the controls (P = 0.032). There were no drug side effects for the case group. Conclusions: A low dose of intravenously administered ketamine had a preemptive effect in reducing pain after appendectomy. (Korean J Pain 2011; 24: 137-140)

Behavior factors for mixed reinforced concrete wall and buckling restrained braced frame

Hamid Beiraghi,Behdad Abbaspour 국제구조공학회 2023 Structural Engineering and Mechanics, An Int'l Jou Vol.86 No.2

A supplementary reinforced concrete wall can be used to improve the seismic behavior of a buckling restrained braced frame as a mixed system. In such a novel system, the total lateral force is resisted by the combination of the RC wall system and the BRBF. There is not enough research on the response modification factor of such a mixed system. This paper investigates the response modification factor, and such relevant factors as ductility reduction factor and over strength factor for a system consisting of reinforced concrete wall and buckling restrained braced frame. To this purpose, nonlinear incremental dynamic analysis as well as static push over analysis are used for 6- to 14-story sample structures. The results show that for mixed considered systems, the mean value of response modification factor varies approximately from 7 to 9.

MUSICAL NOISE REDUCTION BY PROCESSING SPECTROGRAM OF SPECTRAL SUBTRACTION OUTPUT

Hamid Reza Abutalebi,Behdad Dashtbozorg 한국소음진동공학회 2008 한국소음진동공학회 국제학술대회논문집 Vol.2008 No.7

Ischiorectal Block with Bupivacaine for Post Hemorrhoidectomy Pain

Rajabi, Mehdi,Hosseinpour, Mehrdad,Jalalvand, Faranak,Afshar, Mohammad,Moosavi, Golamabbas,Behdad, Samin The Korean Pain Society 2012 The Korean Journal of Pain Vol.25 No.2

Background: Hemorrhoid is one of the most common surgical diseases occurring in the anorectal region. In this study, we evaluated the effect of ischiorectal fossa block on alleviating post hemorrhoidectomy pain. Methods: In this study, 90 patients suffering from hemorrhoids were evaluated. They were randomly divided into 3 groups. The first group had no block, the second group an ischiorectal block with placebo (normal saline), and the third group a preemptive ischiorectal block with bupivacaine. Postoperative variables such as pain intensity, pethidine consumption, nausea, and vomiting were compared between the groups. Results: The postoperative pain score in group 1 was $8.5{\pm}1.3$ and $8.1{\pm}0.9$ (P=NS) in group 2. The post operative analgesic demand was $3.1{\pm}1.5$ and $3.3{\pm}1.8$ hours in groups 1 and 2, respectively (P=NS). The post operative pain score and analgesic demand were $4.2{\pm}2.1$ and $9.3{\pm}2.7$ hours, respectively, in group 3 (P < 0.0001). Conclusions: Preemptive ischiorectal block reduces the posthemorrhoidectomy pain and opioid demand.

Creation of Char from Fossil Carbon Analogous to Biochar

Priscilla Tremain,Lyndal Hugo,Shane Curry,Jafar Zanganeh,Behdad Moghtaderi 한국토양비료학회 2014 한국토양비료학회 학술발표회 초록집 Vol.2014 No.6

Original Articles : Ischiorectal Block with Bupivacaine for Post Hemorrhoidectomy Pain

( Mehdi Rajabi ),( Mehrdad Hosseinpour ),( Faranak Jalalvand ),( Mohammad Afshar ),( Golamabbas Moosavi ),( Samin Behdad ) 대한통증학회 2012 The Korean Journal of Pain Vol.25 No.2

Background: Hemorrhoid is one of the most common surgical diseases occurring in the anorectal region. In this study, we evaluated the effect of ischiorectal fossa block on alleviating post hemorrhoidectomy pain. Methods: In this study, 90 patients suffering from hemorrhoids were evaluated. They were randomly divided into 3 groups. The first group had no block, the second group and ischiorectal block with placebo (normal saline), and the third group a preemptive ischiorectal block with bupivacaine. Postoperative variables such as pain intensity, pethidine consumption, nausea, and vomiting were compared between the groups. Results: The postoperative pain score in group 1 was 8.5±1.3 and 8.1±0.9 (P=NS) in group 2. The post operative analgesic demand was 3.1±1.5 and 3.3±1.8 hours in groups 1 and 2, respectively (P=NS). The post operative pain score and analgesic demand were 4.2±2.1 and 9.3±2.7 hours, respectively, in group 3 (P<0.0001). Conclusions: Preemptive ischiorectal block reduces the posthemorrhoidectomy pain and opioid demand. (Korean J Pain 2012; 25: 89-93)