New Weighted Total Acceleration on Momentum Euler Equation for Formulating Water Wave Dispersion Equation

In this present study, weighted total acceleration for Kinematic Free Surface Boundary Condition (KFSBC) and in momentum Euler equation was formulated. Furthermore, by using both aforementioned equations, the nonlinear water wave dispersion equation was then formulated. The wavelength obtained from dispersion equation is determined by weighting coefficient. The weighting coefficient value was determined by using the maximum wave height and critical wave steepness criteria which have been obtained from the previous studies.

Managing the resilience of future marine specialists to sickness

В статье приводится обоснование условий тренировки устойчивости к укачиванию будущих морских специалистов, способствующих снижению объемов нагрузки в специальных упражнениях и временных затрат на цикл подготовки. Предложен способ расчета перегрузок в упражнениях, применяемых в активной, пассивной и смешанной тренировках устойчивости к укачиванию. Значение критерия определяется путем вычисления отношения полного ускорения, действующего на вестибулярный анализатор в процессе движения, к ускорению свободного падения. Установлено, что ведущей теорией для отбора средств тренировки является теория сенсорного конфликта. Дается описание и обоснование применения авторских разработок для тренировки статического и динамического равновесия на возвышенной, наклонной, качающейся и соскальзывающей опорах, моделирующих условия сохранения статокинетической устойчивости в морских условиях. Предложен необходимый и достаточный комплекс технических устройств и тренажеров для управления устойчивостью будущих морских специалистов к укачиванию. The article substantiates the conditions of resistance to motion sickness of future marine specialists, the possibilities of the system for measuring the load in special exercises and the time spent on the training cycle. A method for calculating overloads in exercises used in active, passive and mixed trainings of resistance to motion sickness is proposed. The value is determined by calculating the ratio of the total acceleration acting on the vestibular analyzer during the acceleration of gravity. It has been established that the leading theory for the selection of training means is the theory of sensory conflict. A description and justification of the use of author's developments for training static and dynamic balance on an elevated, inclined, swinging and sliding support, simulating the conditions for maintaining statokinetic stability in marine conditions, is given. The necessity and a sufficient set of technical devices and simulators for the sustainable development of marine specialists for motion sickness is proposed.

A New Wireless Device for Real-Time Mechanical Impact Evaluation in a Citrus Packing Line

Postharvest handling of fresh fruit is a potential source of bruising and damage, with significant consequences for fruit quality and marketability. In the last 30 years, different types of impact-recording devices (also called electronic fruits or pseudo-fruits) have been developed with the aim of measuring the impacts experienced by fruits during postharvest operations. The aim of this study was to develop and test a novel wireless instrumented sphere to study the critical points in a citrus packing line by measuring the impacts experienced by fruits in real-time. The non-commercial device was based on a MEMS (micro-electro-mechanical system) sensor node with a sensing range from ±1×g to ±400×g (g = 9.8 m s-2), a ferroelectric RAM (FRAM) memory, a radio frequency (RF) transmitter, a microcontroller, and a 75 mAh lithium battery. The sensor node was placed inside a plastic ellipsoid case with a total weight of 100 g to represent a ‘Tardivo di Ciaculli’ mandarin. An FR receiver allowed real-time transmission of the measured data. Tests were performed in the Consorzio del Mandarino Tardivo di Ciaculli packing line (Palermo, Italy). Total acceleration values, representing the stresses experienced by fruit in the packing line, were studied using a variance component model. The results showed that total acceleration remained below 20×g in most of the measurements, but considerably higher values, up to 80×g, were obtained between the brushing and waxing machines. In particular, waxing was identified as the most critical operation based on the impact transmitted to the fruit. Our system proved to be effective for immediate on-line assessment of the accelerations experienced by fruits, allowing prompt intervention to guarantee fruit quality in postharvest operations.HighlightsA novel, wirelessly instrumented sphere was developed and tested to study the critical points in a fruit packing line.The total acceleration experienced by the fruits was studied using a variance component model.The system was proven effective in online assessment of the accelerations experienced by fruits. Keywords: Acceleration, Damage, Instrumented sphere, Mandarin, Postharvest.

Halo acceleration relation

ABSTRACT Recently, from the new Spitzer Photometry and Accurate Rotation Curves data, McGaugh, Lelli & Schombert reported a tight radial acceleration relation between the observed total acceleration and the acceleration produced by baryons in spiral galaxies. The relation can be fitted by different functions. However, these functions can be discerned if we express the data in the form of a halo acceleration relation. The data reveals a maximum in the halo acceleration. We examined the NFW (cusp) and Burkert (core) profiles in the context of dark matter and different parameter families of the interpolating function in the framework of modified Newtonian dynamics.

Acceleration of chemical shift encoding-based water fat MRI for liver proton density fat fraction and T2* mapping using compressed sensing

ObjectivesTo evaluate proton density fat fraction (PDFF) and T2* measurements of the liver with combined parallel imaging (sensitivity encoding, SENSE) and compressed sensing (CS) accelerated chemical shift encoding-based water-fat separation.MethodsSix-echo Dixon imaging was performed in the liver of 89 subjects. The first acquisition variant used acceleration based on SENSE with a total acceleration factor equal to 2.64 (acquisition labeled as SENSE). The second acquisition variant used acceleration based on a combination of CS with SENSE with a total acceleration factor equal to 4 (acquisition labeled as CS+SENSE). Acquisition times were compared between acquisitions and proton density fat fraction (PDFF) and T2*-values were measured and compared separately for each liver segment.ResultsTotal scan duration was 14.5 sec for the SENSE accelerated image acquisition and 9.3 sec for the CS+SENSE accelerated image acquisition. PDFF and T2* values did not differ significantly between the two acquisitions (paired Mann-Whitney and paired t-test P>0.05 in all cases). CS+SENSE accelerated acquisition showed reduced motion artifacts (1.1%) compared to SENSE acquisition (12.3%).ConclusionCS+SENSE accelerates liver PDFF and T2*mapping while retaining the same quantitative values as an acquisition using only SENSE and reduces motion artifacts.Strengths of this studyCompressed sensing allows accelerated imaging with reduction of motion artifacts without alteration of quantitative measurementsRobust results in fat and iron quantification in a heterogeneous patient cohortLimitations of this studyNo histopathological validation of the MR findings was performedThe study was not performed at different field strengths

Measuring torque of galactic bar from Gaia DR2

Since past few decades, observations have improved so strongly that when modelling Milky Way (MW) dynamics it is required to include small perturbations to the modelling process. It is difficult task that we try to solve by selecting regions to model so small that the perturbation can be considered to give nearly constant effect. We use Solar Neighbourhood (SN) as our test sample and assume that the bar effects show more or less constant contribution to SN. By extrapolating and smoothing observed stars on their orbits, and requiring that smoothed and observed phase space are consistent we were able to deduce acceleration vector. We conclude from non-radial acceleration component that the bar must cause about one third of total acceleration near SN.

Análisis del estrés y las exigencias cinemáticas y fisiológicas de los bomberos durante la jornada laboral

El trabajo de los bomberos es considerado como una de las profesiones con mayor exigencia física y predisposición a padecer estrés, debido a las exigentes condiciones de trabajo y la responsabilidad sobre vidas humanas. Los objetivos de la presente investigación fueron: (i) describir las exigencias cinemáticas, fisiológicas y de estrés en bomberos, y (ii) comparar estas exigencias en función de los años de experiencia. Ocho bomberos del parque del Ayuntamiento de Cartagena participaron voluntariamente, siendo divididos en dos grupos en función de la experiencia: (1) experimentados: >12 años (n=4); (2) noveles: <7 años (n=4). Se registraron las variables aceleración total (AcelT), frecuencia cardíaca media (FCmedia) y ratio simpático-parasimpático (R-S|Ps). Los resultados mostraron diferencias entre actividades, encontrando los mayores valores en deporte y salidas. En el análisis inter-grupos, se encontraron diferencias en las variables AcelT y FCmedia en deporte, siendo mayor en los bomberos experimentados (p<.05); y en la variable R-S|Ps en Práctica y Salida con urgencia (p<.05), siendo mayor en los noveles. En conclusión, los bomberos con menos experiencia sufren un mayor estrés durante la jornada laboral. Por tanto, es necesario la incorporación de personal cualificado para diseñar una planificación específica del entrenamiento y de las estrategias de afrontamiento ante la resolución de conflictos adaptadas a la situación real. The work of firefighters is considered one of the professions with greater physical demands and predisposition to suffer stress, due to the hazardous working conditions and the responsibility with human lives. The aims of the present study were to: (i) describe the kinematical, physiological and stress demands of firefighters, and (ii) compare these demands in relation to the experience years. Eight firefighters from the fire department of Cartagena participated voluntarily, dividing them into two groups: (1) experienced: >12 years (n=4); (2) novels: <7 years (n=4). The registered variables were total acceleration (AcelT), heart rate average (HRavg) and sympathetic-parasympathetic ratio (R-S|Ps). The results shown differences between activities, finding the highest values in sport and exits. In the between-groups comparison, differences in AcelT and HRavg in sport (p<.05), being higher in experienced group; and differences in R-S|Ps in practice and exits with urgency (p<.05), being higher in novels group. In conclusion, the firefighters with less experience suffer greater stress during workday. Therefore, it is necessary the incorporation of qualified staff to design specific training and coping strategies before the resolution of conflicts adapted to the real situation.