Tree Biomass Estimation in Karst Forest of West Papua, Indonesia

Indonesia is estimated to have 14,5 million hectares of karst areas. The characteristic of karst vegetation is specific, one of which is the dominance of small trees. With all of the potency, their vegetation acts as a significant carbon sequester and store it in biomass. This study aims to estimate and discuss biomass estimation in the karst forest within the Nature Recreational Park of Beriat, a protected area in South Sorong, West Papua. A total of 28 plots were made in the forest using the purposive random sampling method. Tree biomass (DBH ≥10 cm) was estimated using five different allometric equations. The results showed that the biomass was estimated at ca. 264 Mg ha-1 (95 % CI: 135-454 Mg ha-1). While small trees (DBH 10 – 30 cm) only contribute 30 % of the total biomass, about 38 % of the biomass is the contribution of large trees (DBH >50 cm), where Pometia pinnata contributes ca. 39 % of the biomass at plot-level. The use of various allometric equations results in different biomass estimates and biases with deviations ranged from -14.78 % to +17.02 % compared to the reference equation. Therefore, the selection of allometric equations used must be considered carefully to reduce uncertainties in biomass estimation.

Reference Value for the Distance Walked in the Six-Minute Walk Test in Obese Brazilian Men in the Preoperative Period of Bariatric Surgery

Background. Obesity has several effects on the mechanics of the rib cage that may impair the exercise performance of obese individuals and therefore impact the assessment of surgical risk. This study aimed to establish a reference value for the 6-minute walk distance (6 MWD) in obese Brazilian men in the preoperative period of bariatric surgery that considers the effect of lung function. Methods. This was a cross-sectional study in which 104 obese men underwent the six-minute walk test (6 MWT) before bariatric surgery. They also underwent the spirometry test and respiratory muscle strength measurement before the 6 MWT. Results. The 6 MWD was correlated with age (r = −0.388, p = 0.0005 ), weight (r = −0.365, p = 0.0007 ), height (r = 0.285, p = 0.022 ), body mass index (BMI) (r = −0.543, p < 0.0001 ), forced vital capacity (FVC) (r = 0.472, p < 0.0001 ), peak expiratory flow (r = 0.253, p = 0.031 ), and maximal inspiratory pressure (r = 0.313, p = 0.017 ). In the stepwise forward regression analysis, BMI, FVC, and age were the only variables that independently predicted the 6 MWD and explained 40% of its variability. The reference equation proposed for obese Brazilian men is 6 MWD (m) = 570.5 − (3.984 × BMIkg/m2) + (1.093 × FVC%predicted) − (0.836 × ageyrs). Conclusion. In this sample of obese Brazilian men, lung function contributed to poor performance in the 6 MWT. In these individuals, BMI, FVC, and age were the variables that composed the reference equation for the 6 MWD. Thus, in several clinical settings, such as in the evaluation before bariatric surgery, pulmonary function data are important to determine the reference value for the 6 MWD.

Dynamic Finite Element Modelling And Free Vibration Analysis Of Two Dimensional Elements

DFE is proven to be a powerful tool for analysis of structural problems involving vibration of beams, by introducing frequency dependence in element matrices. This method is extended here to thin plate vibration cases. Lack of previous systematic approach and great performance of beam DFEs were particular drives of the present work. Kirchhoff’s plate bending theory is derived and used as the reference equation describing element behaviour. DFE is implemented in MATLAB® software and evaluated for different conditions. FEM plates are developed for similar geometry using MATLAB® as well and their performance is compared against DFE formulation. Convergence studies are performed and comparisons between FEM and DFE elements are shown. Moreover, critical review of previous works on plate vibrational modelling is made which highlighted the difficulty involved in solving the partial differential equation of plates. Finally comments about the current element and the potential direction of future research are given.

Dynamic Finite Element Modelling And Free Vibration Analysis Of Two Dimensional Elements

DFE is proven to be a powerful tool for analysis of structural problems involving vibration of beams, by introducing frequency dependence in element matrices. This method is extended here to thin plate vibration cases. Lack of previous systematic approach and great performance of beam DFEs were particular drives of the present work. Kirchhoff’s plate bending theory is derived and used as the reference equation describing element behaviour. DFE is implemented in MATLAB® software and evaluated for different conditions. FEM plates are developed for similar geometry using MATLAB® as well and their performance is compared against DFE formulation. Convergence studies are performed and comparisons between FEM and DFE elements are shown. Moreover, critical review of previous works on plate vibrational modelling is made which highlighted the difficulty involved in solving the partial differential equation of plates. Finally comments about the current element and the potential direction of future research are given.

Control of ground objects escorting from aircraft

The synthesis problem of adjuster for software automatic escorting of a ground mobile object using a surveysearch system of an aircraft is considered. The calculation of the control function is carried out by the method of the inverse dynamic problem separately for two angular channels. It is proposed to take into account the restrictions on the magnitude of the control action and on the angles of the line of sight, as well as to use the nonlinear Lewis equation with a correcting differential term as a reference equation. Keywords software support; synthesis of program control; method of the inverse dynamic problem

A reference high-pressure CH4 adsorption isotherm for zeolite Y: results of an interlaboratory study

This paper reports the results of an international interlaboratory study led by the National Institute of Standards and Technology (NIST) on the measurement of high-pressure surface excess methane adsorption isotherms on NIST Reference Material RM 8850 (Zeolite Y), at 25 °C up to 7.5 MPa. Twenty laboratories participated in the study and contributed over one-hundred adsorption isotherms of methane on Zeolite Y. From these data, an empirical reference equation was determined, along with a 95% uncertainty interval (Uk=2). By requiring participants to replicate a high-pressure reference isotherm for carbon dioxide adsorption on NIST Reference Material RM 8852 (ZSM-5), this interlaboratory study also demonstrated the usefulness of reference isotherms in evaluating the performance of high-pressure adsorption experiments.

A Weighted Linear Least Squares Location Method of an Acoustic Emission Source without Measuring Wave Velocity

The location of an acoustic emission (AE) source is crucial for predicting and controlling potential hazards. In this paper, a novel weighted linear least squares location method for AE sources without measuring wave velocity is proposed. First, the governing equations of each sensor are established according to the sensor coordinates and arrival times. Second, a mean reference equation is established by taking the mean of the squared governing equations. Third, the system of linear equations can be obtained based on the mean reference equation, and their residuals are estimated to obtain their weights. Finally, the AE source coordinate is obtained by weighting the linear equations and inserting the parameter constraint. The AE location method is verified by a pencil lead break experiment, and the results show that the locating accuracy of the proposed method is significantly higher than that of traditional methods. Furthermore, the simulation test proves that the proposed method also has a better performance (location accuracy and stability) than the traditional methods under any given scale of arrival errors.