Daily rainfall persistence over Sri Lanka

The spatial distribution of daily rainfall persistence is examined adopting Besson's persistence coefficient and using daily rainfall data for 15 consecutive years (1971-1985). The daily rainfall persistence coefficients have been studied separately for all the twelve months individually and for the whole year. Where January and February indicate the lowest rainfall persistence coefficients the period from October to December indicates the highest coefficients over Sri Lanka. Besides the monsoonal atmospheric conditions, the topography has a strong influence on the rainfall persistence distribution over space and time. The daily rainfall persistence coefficients record higher values in the wet zone then in the dry zone of Sri Lanka. Regression analysis shows a better linear relationship between mean length of wet spell~ and the daily rainfall persistence coefficients and the resultant final equation is y.4' =0.1093+0.1600+X M having the correlation coefficient of 0.721 which is significant at the 0.01% level.

Kissinger Method in Kinetics of Materials: Things to Beware and Be Aware of

The Kissinger method is an overwhelmingly popular way of estimating the activation energy of thermally stimulated processes studied by differential scanning calorimetry (DSC), differential thermal analysis (DTA), and derivative thermogravimetry (DTG). The simplicity of its use is offset considerably by the number of problems that result from underlying assumptions. The assumption of a first-order reaction introduces a certain evaluation error that may become very large when applying temperature programs other than linear heating. The assumption of heating is embedded in the final equation that makes the method inapplicable to any data obtained on cooling. The method yields a single activation energy in agreement with the assumption of single-step kinetics that creates a problem with the majority of applications. This is illustrated by applying the Kissinger method to some chemical reactions, crystallization, glass transition, and melting. In the cases when the isoconversional activation energy varies significantly, the Kissinger plots tend to be almost perfectly linear that means the method fails to detect the inherent complexity of the processes. It is stressed that the Kissinger method is never the best choice when one is looking for insights into the processes kinetics. Comparably simple isoconversional methods offer an insightful alternative.

Mathematical and geometrical modeling of braided ropes bent over a sheave

As soft elements for force transmission, braided fiber ropes play important roles in many fields where the fiber ropes are used bent over sheaves, while the relevant experiments are time-consuming and expensive. Computational simulation is a promising choice for evaluating the performance of fiber ropes when bent over a sheave. This article presents two methods that could be employed to build a model of braided rope bent over a sheave. One is the mathematical method which deduces the exact mathematical equations of braiding curves based on the Frenet–Serret frame. The spatial equations, considering the phase difference of strands in the same direction and the difference of strands’ projection in different directions, are discussed carefully. The final equation of braided strands is confirmed by modeling the braided rope in Maple® 17. The other method, which is inspired by the analysis of braiding movements, is based on the intersection of surfaces of braiding surface and helical surface which are introduced and defined based on the motion analysis of bobbins and take-up roller. The SolidWorks® 2018 is successfully employed to realize the modeling process.

Trail Making Test, Stroop, and Verbal Fluency: Regression-Based Norms for the Icelandic Population

Objective The aim of this study was to construct regression-based norms for 3 executive-function tests: the Trail Making Test, Stroop, and Verbal Fluency. Method A sample of 1,034 healthy Icelandic adults (18–64 years) was used to calculate predicted scores for test measures from all 3 tests, controlled for the effects of age, gender, and education, as well as the interaction between these variables. Results The 3 demographic variables showed significant effects on most test measures and were included in the final equation for estimating predicted scores. An older age and less education predicted worse cognitive performances in most cases, and women tended to outperform men. Conclusion These results highlight the importance of adjusting for age, gender, and educational level when constructing normative data. Controlling for age alone may be insufficient or misleading in clinical-practice settings. A simple, user-friendly program for predicting executive-function test scores is provided.

RANCANG BANGUN SENSOR TEKANAN BERBASIS KOIL DATAR UNTUK MENGUKUR TEKANAN HIDROSTATIS AIR BENDUNGAN RAWAN BANJIR DI WILAYAH LOMBOK NUSA TENGGARA BARAT

Abstrak :Penelitian ini tentang rancang bangun sensor tekanan berbasis koil datar untuk mengukur tekanan hidrostatis air bendungan rawan banjir di wilayah Lombok Nusa Tenggara Barat. Adapun tujuan khusus daripenelitian ini adalah 1) membuat rangkaian pengolah sinyal dari sensor tekanan berbasis koil datar, 2) menentukan besarnya tekanan hidrostatis pada beberapa kedalaman air di bendungan rawan banjir. Jenis penelitian ini adalah eksperimen. Metode penelitian meliputi tahapan yaitu desain elemen sensor koil datar, desain kalibrasi jarak, merancang koil datar, merancang rangkaian digital dan pengiriman data. Variabel yang diukur adalah tegangan keluaran sensor getaran koil datar. Jarak logam pengganggu terhadap koil datar akan berubah setelah rumahan sensor dicelupkan ke dalam air dengan kedalaman h. Semakin besarkedalaman h maka logam pengganggu akan semakin mendekati elemen koil datar. Sensor koil datar diukur responnya terhadap perubahan jarak dari logam pengganggu, kemudian dicatat hasilnya dan dianalisismenggunakan analisis regresi linier pada Ms. Excel. Berdasarkan hasil analisis data diperoleh hasil berupa persamaan Vout dan PH yaitu Vout = 0.000PH – 60.60. Persamaan ini merupakan persamaan akhir yangmenyatakan hubungan linier antara Vout dan PH. Artinya jika kedalaman diubah-ubah secara sembarang maka setiap saat akan diketahui juga nilai tekanan hidrostatis yang ditandai dengan adanya perubahantegangan keluaran pada sensor. Abstract : This research is about the design of flat coil-based pressure sensors to measure hydrostatic pressure of flood-prone water in the Lombok region of West Nusa Tenggara. The purpose of this study is 1) to make a signal processing circuit from a flat coil based pressure sensor, 2) to determine the amount of hydrostatic pressure at some depth of water in a flood-prone dam. This type of research is an experiment. The researchmethods include stages namely the design of flat coil sensor elements, distance calibration design, flat coil design, digital circuit design and data transmission. The measured variable is the flat coil vibration sensoroutput voltage. The distance of the metal to the flat coil will change after the sensor housing is immersed in water with depth h. The greater the depth of h, the more metal will approach the flat coil element. The flat coilsensor is measured in response to changes in distance from the metal, then the results are recorded and analyzed using linear regression analysis on Ms. Excel. Based on the results of data analysis, the results arein the form of Vout and PH equations, namely Vout = 0.000PH - 60.60. This equation is the final equation which states the linear relationship between Vout and PH. This means that if the depth is changed arbitrarily, at anytime it will be known also the value of the hydrostatic pressure which is indicated by the change in the output voltage on the sensor.

Discriminant Analysis to Predict the Hypertension in Women Aged 25–54 Years

BACKGROUND: Hypertension is generally associated with the contributing risk factor for cardiovascular disease in adults. This research is aimed to create a prediction model of the hypertension incidence in women aged 15 through 54 years. MATERIAL & METHODS: The research subjects are 117 women whose ages range from 27 to 54 years living in the village in the central district of Bogor. Through the instrumentation and Vo2 max measuring performed, the information was gathered concerning the following aspects: a) socio-demographic status; b) the abdominal girth; c) fasting blood glucose level; d) body mass index; e) blood lipids including the total cholesterol and triglycerides. The data analysis was conducted using discriminant analysis. RESULTS: The results of multivariable discriminant analysis showed that the level of Vo2 max is the only distinction maker of the incidence of hypertension with the final equation model Zscore = -3.033 + 0.102*Vo2 max and the cut off point -0.00018. CONCLUSION: Concerted efforts from all concerned parties are needed to prevent the hypertension especially through the physical activities relevant to a more quality lifestyle.

Modeling the kinetics of essential oil hydrodistillation from juniper berries (Juniperus communis L.) using non-linear regression

This paper presents kinetics modeling of essential oil hydrodistillation from juniper berries (Juniperus communis L.) by using a non-linear regression methodology. The proposed model has the polynomial-logarithmic form. The initial equation of the proposed non-linear model is q = q??(a?(logt)2 + b?logt + c) and by substituting a1=q??a, b1 = q??b and c1 = q??c, the final equation is obtained as q = a1?(logt)2 + b1?logt + c1. In this equation q is the quantity of the obtained oil at time t, while a1, b1 and c1 are parameters to be determined for each sample. From the final equation it can be seen that the key parameter q?, which presents the maximal oil quantity obtained after infinite time, is already included in parameters a1, b1 and c1. In this way, experimental determination of this parameter is avoided. Using the proposed model with parameters obtained by regression, the values of oil hydrodistillation in time are calculated for each sample and compared to the experimental values. In addition, two kinetic models previously proposed in literature were applied to the same experimental results. The developed model provided better agreements with the experimental values than the two, generally accepted kinetic models of this process. The average values of error measures (RSS, RSE, AIC and MRPD) obtained for our model (0.005; 0.017; ?84.33; 1.65) were generally lower than the corresponding values of the other two models (0.025; 0.041; ?53.20; 3.89) and (0.0035; 0.015; ?86.83; 1.59). Also, parameter estimation for the proposed model was significantly simpler (maximum 2 iterations per sample) using the non-linear regression than that for the existing models (maximum 9 iterations per sample).

Towards improving the applicability of the RUSLE model at mountainous Mediterranean catchments

<div> <p>In here we present a modified version of the RUSLE model, which can perform better than the original version at mountainous, Mediterranean catchments. A weighing coefficient is assigned at each factor in the model resulting into a reduction in the model residuals (difference between modeled and observed sediment yield). Observations are based on sediment discharge measurements conducted by the Greek Public Power Corporation (PPC). The study area includes the catchments of Venetikos, Kalamas, Arachthos and Acheloos Rivers, which are very important aquatic systems of northwestern Greece. The cross&minus;evaluation between the originally simulated (no coefficients) and observed sediment yields attributed an initial error term value of 40 213.06t ha^&minus;1. Subsequently, the model was modified (weighing coefficients were assigned regarding the PPC measurements) and the same procedure was followed, reducing the error term value to 25 937.07t ha^&minus;1. The ambiguous reliability of the PPC measurements led to their replacement by simulations using the sediment discharge rating curves methodology. The modified RUSLE model is based on different weighing coefficients assigned regarding the rating curves estimations. Results show that the error term was moreover reduced to 5 834.78t ha^&minus;1. The final equation was implemented to each subcatchment both at an annually and inter-annually scale in order to validate the model&rsquo;s reliability. Overall, the results were satisfactory.</p> </div> <p>&nbsp;</p>

A head loss model for homogeneous slurry transport for medium sized particles

Slurry transport in horizontal and vertical pipelines is one of the major means of transport of sands and gravels in the dredging industry. There exist 4 main flow regimes, the fixed or stationary bed regime, the sliding bed regime, the heterogeneous flow regime and the homogeneous flow regime. Of course the transitions between the regimes are not very sharp, depending on parameters like the particle size distribution. The focus in this paper is on the homogeneous regime. Often the so called equivalent liquid model (ELM) is applied, however many researchers found hydraulic gradients smaller than predicted with the ELM, but larger that the hydraulic gradient of liquid. Talmon (2011, 2013) derived a fundamental equation (method) proving that the hydraulic gradient can be smaller than predicted by the ELM, based on the assumption of a particle free viscous sub-layer. He used a 2D velocity distribution without a concentration distribution. In this paper 5 methods are described (and derived) to determine the hydraulic gradient in homogeneous flow, of which the last method is based on pipe flow with a concentration distribution. It appears that the use of von Driest (Schlichting, 1968) damping, if present, dominates the results, however applying a concentration distribution may neutralise this. The final equation contains both the damping and a concentration distribution giving the possibility to calibrate the constant in the equation with experimental data. The final equation is flexible and gives a good match with experimental results in vertical and horizontal pipelines for a value of ACv = 1.3. Data of horizontal experiments Dp = 0.05-0.30 m, d = 0.04 mm, vertical experiments Dp = 0.026 m, d = 0.125, 0.345, 0.560, and 0.750 mm.

Age determination in dogs using ocular light reflection, dental abrasion and tartar

SummaryObjective: The knowledge of an animal’s age is important for disease probability, prognoses, or epidemiological questions, but unfortunately, it is often unknown for dogs in animal shelters. A simple estimating procedure is preferable being quick and easy to perform, even for nonveterinarians. Material and methods: In 295 dogs the dimension of light reflection (diameter in millimetres), visible on the posterior lens capsule using a penlight, the grade of dental abrasion and dental tartar were documented photographically and the exact weight and age in days were obtained. These photographs were evaluated blinded. The dogs were divided randomly into two groups. The first group was used to establish a model for age determination using linear and logistic regression models considering the documented parameters, which was then validated with the data of the second group. Results: The size of ocular light reflection and age correlated significantly (r = 0.781; p < 0.001; sy,x = 2.45 years [SD of y for given x]). The linear regression model gave the final equation: Estimated age [months] = 13.954 + 33.400 × lens reflection [mm] + 8.406 × dental abrasion [grade] + 8.871 × tartar [grade] with a standard error of estimation of 2.26 years. Conclusion and clinical relevance: Age determination, even based on three parameters results in a large standard deviation making age estimation in dogs very crude.