Progressive collapse analysis of steel frames: Simplified procedure and explicit expression for dynamic increase factor

Progressive collapse refers to a phenomenon in which local damage in a primary structural element leads to total or partial structural system failure. When investigating the progressive collapse of structures, nonlinear dynamic procedures lead to more accurate results than static procedures. However, nonlinear dynamic procedures are very complicated and the evaluation or validation of the results can become very time consuming. Therefore, it is better to use simpler methods. For static analyses, the gravity force applied to the removed column bay should be multiplied by a constant factor of two. However, using a constant dynamic increase factor (DIF) is only appropriate for elastic systems. According to the optimal design of structures, the assumption of elastic behavior after column removal is conservative. Thus, it is necessary to establish an expression for DIF that considers inelastic responses. In this paper, a simplified analysis procedure for the progressive collapse analysis of steel structures is presented using the load displacement and capacity curve of a fixed end steel beam. The results of the proposed method are in good agreement with nonlinear dynamic analysis results. Also, the capacity curve, obtained by dividing the accumulated area under the nonlinear static load displacement curve by the corresponding displacement of the column removed point, is used to predict the progressive collapse resistance of the column removed structure. Finally, an explicit expression for the DIF is established for elastic-perfectly plastic and elastic plastic with catenary action behavior.     

Hydrierung von p‐Nitrophenol zu p‐Aminophenol als Testreaktion für die katalytische Aktivität von Pt‐Trägerkatalysatoren

The hydrogenation of p‐nitrophenol (PNP) to p‐aminophenol (PAP) using NaBH₄ as a reducing agent was studied as a test reaction for determining the catalytic activity of supported Pt catalysts. The initial reaction rate, which is accessible within less than 10 minutes via online UV‐vis spectroscopy at room temperature, ambient pressure and in water as a solvent, was used as measure for the catalytic activity. For three Pt catalysts supported on porous SiO₂, porous glass and Al₂O₃, respectively, significant differences in the catalytic activity were observed. However, especially in case of very active catalysts, limitations of the reaction by internal or external mass transfer have to be considered.     

Determination of Heterocyclic Amines in Meat Matrices Using Enhanced Matrix Removal‐Lipid Extraction and Liquid Chromatography–Tandem Mass Spectrometry

A simple, fast, and efficient method, “enhanced matrix removal of lipids” (EMR‐lipid), was proposed, optimized, and validated for identifying five polar heterocyclic amines (HCAs) in meat samples that ranged from high‐protein (beef and chicken) to high‐fat (pork bacon) matrices. The protocol involves an initial solid–liquid phase extraction followed by a rapid dispersive solid‐phase extraction using EMR‐lipid sorbents and salting‐out partitioning. Acetonitrile containing formic acid at two levels (1% and 2%) efficiently extracted HCAs from different meat matrices. Liquid chromatography–tandem mass spectrometry (MS/MS) with selective reaction monitoring mode was developed for qualitative and quantitative analysis. The highest MS/MS responses and better peak separation of analytes were achieved by adjusting mobile phases to pH 3.0 with instrumental detection limits between 0.01 and 0.05 ng/mL. Good linearity of standard curves was obtained in both pure solvents and postspiked meat extracts between 0.5 and 50.0 ng/mL. The validation results showed good precision, accuracy, and sensitivity for detecting HCAs in spiked meat samples. Satisfactory recoveries of four HCAs were achieved: 65% to 111% in beef, 71% to 106% in bacon, and 42% to 77% in chicken. Matrix effects were also assessed and showed less than –20% of ion suppression in bacon extract, while a medium to high signal suppression was observed in beef (–37% to –55%) and chicken (–28% to –52%). This optimized EMR‐lipid method provides acceptable results and advantages for determining trace level HCAs in complex meat matrices.     

Experimentally validated analytical modeling of diesel exhaust HC emission rate

Supercharged diesel engines are a key source of hazardous regulated emissions that have been extensively modelled, yet without explainable mathematical trends. The present paper demonstrates the analytical modeling of the percentage of unburned Hydrocarbon and the HC emission rate in four-stroke diesel engines for trucks. The study presents as well the analytical modeling of the supercharged air density. A sensitivity analysis has been conducted on these developed models. The study shows that the average percentage of deviation of the simulated results from the corresponding freeway cycles field data on the percentage of unburned Hydrocarbon and the HC emission rate is 10.6% and 4%, respectively. The corresponding coefficient of determination is 70% and 83%, respectively. The relative error of the developed models of the percentage of unburned Hydrocarbon and the HC emission rate is 10.6% and 2%, respectively. The study demonstrates with 99% coefficient of determination that the average percentage of deviation of the simulated results from the corresponding field data under the steady speed operating condition for all freeway cycles on the supercharged air density is 3.7%. The relative error of the developed model of the supercharged air density is 4%. These values of relative error are in an order of magnitude of deviation that is less than that of widely recognized models in the field of vehicle powertrain modeling, such as the CMEM. These developed analytical models serve as widely valid models that follow entirely from the principles of physics and the results of these developed models have explainable mathematical trends. The fact that these developed models are dimensionally correct further supports the validity of these models. The present models can help in better analyzing the performance of diesel engines and in developing and assessing the performance of these engines.     

Life expectancy after total hip arthroplasty

A total of 3,807 patients undergoing total hip arthroplasty (THA) between the years 1970 to 1995 were evaluated for mortality. Patient age groups were designated in 10-year intervals as follows: age <40; 41-50; 51-60; 61-70; 71-80; age >80. The life expectancy estimate of the patients with THA was calculated by the Kaplan-Meier method, and that of the normal population was obtained from standard life-tables. Statistical significance was evaluated using 95% confidence limits. A significant difference in life expectancy was found in patient age groups >60 (61-70, 71-80, >80) demonstrating significantly higher survival rates among THA patients when compared with the normal population.     

Percutaneous management of a bladder-drained pancreas transplant pseudocyst by a transcystic approach

BACKGROUND: We describe a 35-year-old male type 1 diabetic who underwent a cadaveric combined kidney-bladder-drained pancreas transplant with a duodenocystostomy for exocrine drainage who developed a large pelvic pseudocyst associated with a dilated pancreatic duct and an elevated serum amylase level. METHODS: Due to the risk of surgical revision and the possibility of creating a cutaneous fistula with conventional percutaneous drainage, a pseudocyst-to-bladder drainage was performed. After the procedure, the catheter was capped to allow drainage of the pancreatic secretions into the bladder. RESULTS: After drainage, the patient's serum amylase and lipase normalized along with resolution of the pseudocyst. The tube was removed after 19 weeks with no evidence of a recurrent pseudocyst and a normal serum amylase level. CONCLUSION: The percutaneous pseudocyst-cystostomy obviated the need for surgical revision of the exocrine gland drainage and thus eliminated the morbidity and the potential risk of graft loss associated with such surgery.     

Accuracy and variability of leg velocities during concentric and eccentric actions of the quadriceps femoris muscles

This study examined the ability to control leg velocities during concentric and eccentric actions of the right quadriceps muscles. Ten healthy women (M age = 25.9 +/- 3.5 yr.) were tested using the Isotonic Program of the KIN-COM II 500H dynamometer. They attempted to match velocity tracings of 10 degrees, 20 degrees, and 40 degrees/sec. through 70 degrees of knee range of motion at a load equal to 10% of their maximal mean concentric force. The actual mean velocities, mean percent deviation from the target velocities, and the coefficient of variation for both actions were calculated for 15 degrees-75 degrees (full range of motion), 15 degrees-45 degrees (shorter range of motion), and 46 degrees-75 degrees (longer range of motion). Separate one-way analyses of variance with two trial factors (action x velocity) showed faster concentric velocities through the full and longer ranges of motion, and faster eccentric velocities through the shorter range of motion. Mean percent deviations indicated that the eccentric velocities were generally more accurate within all ranges of motion. Larger concentric coefficients of variation were found within the full and longer ranges of motion, and the coefficients of variation for both actions decreased as the velocities increased. An exaggerated 'velocity overshoot' at the onset of both actions probably contributed to differences in the velocities and coefficients of variation. The results indicated differences between the concentric and eccentric actions, explained in part by the testing methodology used and by the known mechanical and physiological characteristics of the two muscle actions.     

Measuring height of high-voltage transmission poles using unmanned aerial vehicle (UAV) imagery

Aerial imagery is important in remote sensing applications. Unmanned aerial vehicle (UAV) has a wide range of applications in remote sensing and presents a substantial cost-effective solution when monitoring objects on the earth’s surface. Moreover, object detection and classification are important aspects of global information system, especially for remote sensing applications and power line monitoring, which are essential for the proper distribution of electricity to consumers. Manual inspection consumes much time and involves risk, especially in remote areas that host dangerous wildlife; hence, UAV-based approaches are more feasible for such monitoring. The authors propose an UAV approach that utilises a digital surface model and incorporates a stereo matching algorithm based on UAV stereo images. The proposed algorithm was based on a graph-cut (GC) algorithm that measured the disparity map. Results were compared with well-known algorithms; including, for example, global and local stereo matching algorithms. The proposed solution introduces and integrates ordering constraints along with a submodular energy minimisation function to/with the GC algorithm to enhance performance. The authors measured sensitivity and recall for all parameters against ground truth data for differently cropped images of 16 power poles. Results showed that the proposed model performed more accurately compared to extant methods.     

P(N) approximation for frequency-domain measurements in scattering media

Presented here are expressions for the P(N) approximation for light propagation in scattering media in the frequency domain. To elucidate parametric dependencies, the derivation uses normalization of the resulting expressions to either the total interaction coefficient or the reduced total interaction coefficient. For the latter case, a set of reduced phase function coefficients are introduced. Expression of the P(N) approximation as a conventional eigenvalue problem facilitates computation of the eigenvalues or attenuation coefficients. This approach is used to determine the attenuation coefficients in the asymptotic regime over the full values of the scattering albedo and reduced scattering albedo (0 to 1) and all positive values of the asymmetry factor (0 to 1). Frequency-domain measurements yield a sensitivity to turbid media optical properties for reduced scattering albedos as small as 0.2. P(N) calculations are used to assess the magnitude of errors associated with the P1 and P3 approximations over a range of scattering albedo, phase function, and modulation frequency.