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Objective: To report on the frequency of healthcare-associated urinary tract infections (UTI) related to its microbiological profile in a tertiary medical facility. Methods: Using a cross-sectional methodology design, the frequency and microbiological profile were analyzed using measures of central tendency. The study was performed after permission from institutional authorities. Results: A total of 806 patients were included in a 2-year period, (2021-2022), of whom 50.6% were male. Only 15.4% of UTI associated with healthcare were informed as official federal standards indicate (NOM-045-SSA2-2005). From the total cohort, 76.2% of reported cases were UTI associated with bladder catheterization. Escherichia coli was the most frequent isolated microorganism, while, Acinetobacter baumannii was the pathogen with the highest resistance. Conclusion: Healthcare-associated infections (HAIs) are one of the most common problems while a patient is hospitalized. Today, the World Health Organization considers them as a global public health concern since human lives are at risk and economic issues are affecting health systems worldwide. Independently of the HAIs type, measures for control and prevention should be applied by health personnel in a multidisciplinary way. [ABSTRACT FROM AUTHOR]

Entropy measurements are an accessible tool to perform irregularity and uncertainty measurements present in time series. Particularly in the area of signal processing, Multiscale Permutation Entropy (MPE) is presented as a characterization methodology capable of measuring randomness and non-linear dynamics present in non-stationary signals, such as mechanical vibrations. In this article, we present a robust methodology based on MPE for detection of Internal Combustion Engine (ICE) states. The MPE is combined with Principal Component Analysis (PCA) as a technique for visualization and feature selection and KNearest Neighbors (KNN) as a supervised classifier. The proposed methodology is validated by comparing accuracy and computation time with others presented in the literature. The results allow to appreciate a high effectiveness in the detection of failures in bearings (experiment 1) and ICE states (experiment 2) with a low computational consumption. [ABSTRACT FROM AUTHOR]

This paper develops a model for studying the effect of joint clearances on the end-effector's loci for planar parallel manipulators with 2 degree-of-freedom (DOF). The condition for developing end-effector loci equations with respect to the joint clearance relies on the fact that at least one point of contact is always presented in each joints. The motivation of this work lies in the fact that the proposed procedure allows the study of parallel manipulators that can be considered as design concepts for developing an x-y cutting table for a textile industry. Numerical simulations enable to compare three 2-DOF planar parallel manipulators architectures: i) 2-RRR, ii) 2-RPR, and iii) 2-RPR. A Monte Carlo simulation allows us to find the area of possible end-effector locations for a specific value of clearance. Also, the equations allow us to find the largest distance from the desired location to the one obtained considering clearance. Findings shed some lights on establishing which parallel manipulator is less affected to joint clearance. [ABSTRACT FROM AUTHOR]

Fault diagnosis of an internal combustion engine is proposed herein by means of vibration analysis and a comparative analysis of normal operation and induced misfire scenarios. In order to validate previous works on misfire with pure gasoline, measurements also included tests performed with ethanol-gasoline fuel blends. According to results, changes in the fuel mix seem to have little impact on the performance and behaviour of the engine. And additionally, the particular frequency components that allowed differentiation between normal and faulty conditions were also present on all the fuel blends tested. Fast Fourier Transform was applied to obtain the frequency domain of the signal as a previous step to the subsequent identification process based on statistical characteristics extraction. A fuel blend classification method based on the analysis of the vibration signals of the engine was studied using envelope, Spike Energy and Peak Value techniques. Differentiation was possible with the extraction of the statistical features of the Peak Value spectrum of the longitudinal acceleration with a specific filter selection. [ABSTRACT FROM AUTHOR]

An estimation method of the combustion chamber pressure, in an internal combustion engine, based on the processing of the vibration (acceleration) signal of the cylinder head, at constant speed and no load conditions is presented in this paper. The model is created based on the comparison of the vibration and pressure signals around the peaks of highest vibration, after a preprocessing and filtering of the signal using the most similar frequency bands between the sources. A polynomial regression is used between the selected data points to generate the resulting model relating pressure and vibration (and average rotational speed per cycle, calculated based on the vibration peaks). The model is tested with measurements from two spark ignited engine test benches: a single cylinder engine and a four-cylinder engine. The resulting model has very low computational cost and can provide a very accurate estimation of general shape and magnitude of the pressure trace, but does not reflect strongly cycle by cycle variations. Testing the Normalized Root Mean Square Error (NRMSE), where the best value is 100 % the single cylinder engine scores were 63.52 % and 20.02 % for the points before and after the vibration peak. For the four‑cylinder engine those values were: 82.47 % and 28.27 % respectively. [ABSTRACT FROM AUTHOR]

A new mathematical periodic function, called VAP function, is proposed for the design of cam-follower mechanisms. With the VAP function, a given variable increases and decreases almost linearly from its minimum and maximum values, respectively, while the function and its derivate are smooth. As a case study, the design of a disc cam with a translating roller follower is considered, using four displacement laws: one based on a 4-5-6-7 polynomial displacement function, one based on a harmonic function, and two based on the VAP function. A comparative dynamic and kinematic analysis is shown. It is concluded that the cam-follower mechanism designed with the VAP function has smaller input torques, as well as lower pressure angles, than the one designed with harmonic function and that the one with 4-5-6-7 polynomial function. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to measure the frequency of complications associated with uretero-ureteral anastomosis (UUA) in patients with a history of renal transplantation. Methods: An analytical cross-sectional study was carried out in which clinical records of patients with a history of renal transplantation were reviewed. Patients treated with UUA after a urological complication was selected. All of the above, with the permission of the institutional authorities and the Ethics Committee. For the statistical analysis, measures of central tendency, frequencies, and proportions were used. Results: A total of 24 patient files were identified that met the inclusion criteria. A total of 16.6% (n = 4) of the patients presented complications after UUA. The most frequent complication was urinary leakage. Variables such as sex and chronic degenerative diseases were included in the study. There was no significant difference between groups using these variables. Only serum creatinine presented values of p < 0.01. Conclusion: The present study shows that UUA is a safe procedure that offers a considerable decrease in the incidence of complications when compared to other less invasive strategies such as JJ catheter placement or nephrostomy. In general terms, it improves the quality of life and the functional time of the graft in the face of an early complication. [ABSTRACT FROM AUTHOR]

Objective: The present work aimed to measure the changes in biological markers in patients during and after percutaneous nephrolithotomy (PNL). Methods: A cross-sectional study was performed in patients managed with PLN. Biological markers were measured at three different times. Measures of central tendency and mean difference were used to describe the population and biological markers. A significant value was considered if p < 0.05. Results: A total of 23 patients with a diagnosis of renal lithiasis managed with PNL were included. The sample included 73.9% of woman with a mean age of 47.96 years. About 26% presented some post-surgical complication. Changes observed in the biological markers: hemoglobin and platelet levels showed a tendency to decrease post-surgery (p < 0.05). Leukocyte, neutrophil, and C-reactive protein levels showed a significant increase in the post-operative period. The DHL and erythrocyte sedimentation rate presented elevation during the post-operative period; however, after the surgical event, they decreased. Conclusions: We can assume the degree of metabolic response and establish preventive measures for possible complications. The implementation of protocols with the use of biomarkers can be useful in the identification of risk factors for complications during and after the surgical event. [ABSTRACT FROM AUTHOR]

Compression‐ignition (CI) engines, aka diesel engines, are responsible for an essential percentage of the world‐polluting emissions. Moreover, bearings installed in industrial machinery constitute the most common failure affecting global energy consumption. Since industries' energy demand has a growing tendency, efficient maintenance is a must. Maintenance requires a fast and accurate diagnosis, commonly based on an intrusive or expensive sensor to capture monitoring signals, i.e. pressure, emissions, temperature, fuel consumption and rotational speed. Here, a vibration signal‐based approach is introduced to combustion engines and bearings diagnosis. Namely, a multi‐scale permutation entropy (MPE)‐based feature extraction is conducted within a variability‐based relevance analysis (VRA) stage to feed a straightforward classifier, the K‐nearest neighbours (KNN). Accuracy was validated using a signals' database from a single‐cylinder engine under multiple work conditions. Also, the methodology is compared through classification accuracy of a widely known bearing vibration signal database obtaining an outstanding performance. [ABSTRACT FROM AUTHOR]

Internal combustion engines are complex machines that constitute an object of design, and in which diverse processes and variables encounter. In the industrial field, the design of a new engine begins with the conception of a wellestablished solution with consideration on the experience of the designers. To perform the structural design of an engine, it is needed to determine the forces and moments acting on its components, derived from the processes along the cycles of work, with observation of the variations of the pressures and the temperatures in the cylinder and of the forces and moments of inertia in the components of the mechanisms and the structure. It is the purpose of the present paper to introduce the development of a series of procedures to obtain the preliminary dimensions of the main components of an engine (power mechanism, engine block and cylinder head dimensions), applying the machine design fundamentals and the thermodynamic and dynamic characterization of a generic engine of combustion, using the minimum information (power, torque, engine speed, and conditions of exploitation). To systematize the engine preliminary design, a spreadsheet based on Microsoft Excel was developed. To use this spreadsheet, the user must specify composition of the fuel, the type of ignition, and the wished characteristics of the engine. The outputs of the spreadsheet are the global stoichiometric balance of fuel-air chemical reactions, the heat release rate, the indicator diagram, the forces and moments acting on the main components of the crank-train mechanism, such a valuable information required to conduct the dimensioning of the engine components making use of the fundamentals of strength of materials. [ABSTRACT FROM AUTHOR]

This paper presents the vibration analysis of an internal combustion engine, using different fuel blends, to identify fault operating conditions. A purpose built engine test bench was used and the fault studied was misfire. Three fuel blends were used: E8, E20 and E30. Fast Fourier transform was applied to the signals. A comparison between normal and faulty operating conditions was carried with every fuel used, looking for characteristic frequency components, to assess the validity of past studies on misfire performed on pure gasoline. The results show that the behavior using the different fuel blends is similar to the one reported on pure gasoline, and that the frequency components that differentiate normal and faulty conditions are also present on the fuel blends. Statistical characteristics were extracted from the signals in the frequency domain to simplify the identification process. [ABSTRACT FROM AUTHOR]

The experimental validation of a mathematical ball bearing model with localized outer race defects is presented in this paper. The bearing is considered as a mass -- spring -- damper system, considering each rolling element as a contact spring -- damper pair, based on Hertz equations for contact deformation, moving along the races. In accordance with the obtained results, in this work a bearing model is validated with a purpose built test bench. To compare the vibration signals from the real system and the model, spectral and high frequency analysis is used, particularly techniques commonly used on commercially available vibration analysis equipment, such as envelope and Peak Value analysis. The studied model shows a frequency behavior similar to that of the experimental data and the envelope and Peak Value analysis clearly reveal the characteristic frequencies of the studied type of defects. [ABSTRACT FROM AUTHOR]

In this work, a methodology to diagnose ten diesel bus engines is carried out by means of some characteristics of the starting system performance. The signals of battery voltage, electric current supplied to the starter motor and crankshaft revolutions during cold and warm engine starting processes are analysed. Characteristics and patterns of the signals that are attributable to engine compression and combustion failures are pointed out, which are related to the kilometres travelled by each vehicle after the last engine repair and the shutdown time of the engine in warm condition. It is obtained that the rise of the current required by the starter motor during the second and third compression process, and the mean crankshaft angular acceleration after the second compression process are characteristics that are related to the engine condition. [ABSTRACT FROM AUTHOR]

Sand and gravel mining on rivers causes erosion or incision of the river bed, upstream erosion in tributaries, damage to different structures (bridges, water intakes, dykes, bank protection works, houses and roads), and, it alters the river equilibrium, affecting the fluvial ecosystem. In order to minimize the negative effects a methodology is proposed for estimating the maximum annual extraction volumes, based on the annual sediment transport of the river, in other terms, on the natural replenishment rate. Initially it is important to carry out an integral study of the river to understand the fluvial dynamics, including the different aspects (hydrology, hydraulics, sediment transport.) with emphasis on the geomorphologic processes and the identification of other aspects (dams, intakes, protection works.) that could be affecting it. The possible areas of aggradation should be estimated, this is, the areas that are potentially exploitable, and the morphological changes due to the mining activities should be estimated. The proposed methodology also requires a periodic monitoring of the bed load and of the variation of the river bed levels, the updating of the annual sediment loads duration curve and the forecasts of the river discharges for a given year. [ABSTRACT FROM AUTHOR]