Evaluating the Sensitivity of Forest Structural Diversity Characterization to LiDAR Point Density

Recent expansion in data sharing has created unprecedented opportunities to explore structure-function linkages in ecosystems across spatial and temporal scales. However, characteristics of the same data product, such as resolution, can change over time or spatial locations, as protocols are adapted to new technology or conditions, which may impact the data’s potential utility and accuracy for addressing end user scientific questions. The National Ecological Observatory Network (NEON) provides data products for users from 81 sites and over a planned 30-year time frame, including discrete return Light Detection and Range (LiDAR) from an airborne observatory platform. LiDAR is a well-established and increasingly available remote sensing technology for measuring three-dimensional (3D) characteristics of ecosystem and landscape structure, including forest structural diversity. The LiDAR product that NEON provides can vary in point density from 2 – 25+ points/m2 depending on instrument and acquisition date. We used NEON LiDAR from five forested sites to (1) identify the minimum point density at which structural diversity metrics can be robustly estimated across forested sites from different ecoclimatic zones in the USA and (2) to test the effects of variable point density on the estimation of a suite of structural diversity metrics and multivariate structural complexity types within and across forested sites. Twelve out of sixteen structural diversity metrics were sensitive to LiDAR point density in at least one of the five NEON forested sites. The minimum point density to reliably estimate the metrics ranged from 2.0 to 7.5 pt/m2, but our results indicate that point densities above 7-8 pt/m2 should provide robust measurements of structural diversity in forests for temporal or spatial comparisons. The delineation of multivariate structural complexity types from a suite of 16 structural diversity metrics was robust within sites and across forest types for a LiDAR point density of 4 pt/m2 and above. This study shows that different metrics of structural diversity can vary in their sensitivity to the resolution of LiDAR data and users of these open-source data products should consider the point density of their data and use caution in metric selection when making spatial or temporal comparisons from these datasets.

EXPLORING GIFTED AND TALENTED MUSLIMS STUDENT’S PERFORMANCE USING GEOGEBRA IN TEACHING AND LEARNING MATHEMATICS

GeoGebra is a teaching tool that educators use in their lesson plans to improve the quality of teaching and learning. Instead of drawing on a sheet of paper, students can design a graph, adjust the actual graph shape, and examine the impact of changing graph pattern using GeoGebra in mathematics teaching and learning. Furthermore, students can keep all of their work materials in a structured manner for future reference. GeoGebra will make a school lecture more interesting, exciting, creative, and innovative. The goal of this study was to analyse the effects of GeoGebra software in Mathematics achievement in respect to quadratic functions among gifted and talented Muslims student’s at Kolej GENIUS Insan, Universiti Sains Islam Malaysia. The maximum or minimum point of quadratic function was determined by using GeoGebra software, and the characteristics of quadratic expressions in one variables was also identified. The results illustrate that the graph quadratic expression has the highest point or the lowest point based the values of coefficient a on the quadratic function. For the graph function with negative values of coefficient a on a quadratic function, there are highest values of coordinates x and y, which also known as maximum point, while the graph function with positive values of a on a quadratic function, there are lowest values of coordinates x and y, which also known as minimum point. When students utilize GeoGebra software, their performance in calculating the minimum and maximum points on quadratic functions improves. Keywords: Geogebra; Integrated naqli ‘aqli gifted education; Gifted muslims student; Mathematics achievement; Quadratic functions

Simulation-Based Optimization for Convex Functions Over Discrete Sets

We propose a new iterative algorithm for finding a minimum point of f_*:X \subset \mathbb{R}^d \rightarrow \mathbb{R}, when f_* is known to be convex, but only noisy observations of f_*(\textbf{x}) are available at  \textbf{x} \in X for a finite set X. At each iteration of the proposed algorithm, we estimate the probability of each point \textbf{x} \in X being a minimum point of f_* using the fact that f_* is convex, and sample r points from X according  to these probabilities. We then make observations at the sampled points and use these observations to update the probability of each point \textbf{x} \in X  being a minimum point of f_*. Therefore, the proposed algorithm not only estimates the minimum point of f_* but also provides the probability of each point in X being a minimum point of f_*. Numerical results indicate the proposed algorithm converges to a minimum point of f_* as the number of iterations increases and shows fast convergence, especially in the early stage of the iterations.

DINAMISASI KABINET DAN UPAYA KONSISTENSI SISTEM PRESIDENSIAL DI INDONESIA

Dinamisasi kabinet kerja yang merupakan hak prereogratif presiden tidak hanya memperhatikan resistensi antara presiden dengan kepentingan partai politik, namun juga pertimbangan antara eksistensi Pemerintah Daerah sebagai konsekuensi dari sistem Presidensil dalam bentuk Negara Kesatuan Republik Indonesia. Tulisan ini berusaha menelaah topik pembahasan Dinamisasi Kabinet dan Upaya Konsistensi Sistem Presidensial di Indonesia. Metode penelitiаn ini аdаlаh yuridis normаtif dengan pendekatan historis, pendekatan konseptual, dan pendekatan peraturan perundang-undangan. Hasil dalam pembahasan ini menyimpulkan bahwa postur kabinet harus dibarengi dengan sinkornisasi hukum hingga pada titik minimum postur pemerintahan (Pemerintah Daerah) dengan Pemerintah Pusat yang direpresentasikan oleh kementerian melalui UU Nomor 23 Tahun 2014 tentang Pemerintah Daerah dengan UU Nomor 39 tahun 2008 tentang Kementerian. Bentuk sinkornisasi tersebut dapat dilakukan melalui: Penambahan unsur profesionalisme dalam UU, Penambahan peraturan terkait komposisi, dan/atau syarat, dalam penambahan/ pengubahan/ penghapusan kementerian, dan penambahan pengaturan terkait harmonisasi kewenangan dan ruang kerja antara pusat dan daerah.Kata kunci: Dinamisasi, Kabinet, Pemerintah. The dynamism of the working cabinet, which is the president's prerequisite, not only takes into account the resistance between the president and the interests of political parties, but also the consideration between the existence of the Regional Government as a consequence of the Presidency system in the form of the Unitary State of the Republic of Indonesia. This paper attempts to examine Cabinet Dynamics and Efforts to Consistency in the Presidential System in Indonesia. This research method is juridical normative with a historical approach, a conceptual approach, and a statutory approach. The results of this discussion conclude that the cabinet posture must be accompanied by legal syncornization to the minimum point of government posture (Regional Government) with the Central Government represented by the ministry through Law Number 23 of 2014 concerning Regional Government with Law Number 39 of 2008 concerning Ministries. This form of syncornization can be carried out through: Adding elements of professionalism in laws, adding regulations related to composition, and/or requirements, adding/ changing/ deleting ministries, and adding regulations related to harmonization of authority and work space between the central and regional governments.Keywords: Cabinet, Dynamism, State Government

PROPERTIES OF THE REACTIVE POWER OF THE ASYNCHRONOUS MACHINE AS A LOAD OF THE ELECTRIC NETWORK

It is known that the voltage mode of the electrical network is associated with the balance of reactive power and directly affects the operation of production equipment. A typical static characteristic of a power supply unit in terms of reactive power, obtained for a load composition characteristic of electrical networks, is an extreme function with a minimum point. It is the presence of a minimum point in the dependence of reactive power on voltage that makes it possible to develop this type of instability as a voltage avalanche. This mode is especially dangerous for industrial units with abruptly variable loads, which can create significant fluctuations in the supply voltage, which significantly affects the operation of powerful asynchronous motors. Therefore, the issues of the relationship between the parameters mode of the electrical network and the properties of electrical loads are always important, especially asynchronous machines as the main consumer of electricity, which largely determines the properties of the generalized reactive power curve of the entire load unit. Literary sources do not explain in detail why the curve of the dependence of the reactive power of the power supply unit on voltage has a minimum. The article sets out this issue in sufficient detail for asynchronous machines as the main consumer of reactive power in electrical networks. The task is to obtain the dependence of the reactive power of an induction machine with a squirrel-cage rotor on the voltage of the supply network, as well as to determine the criteria for controlling reactive power flows in order to inadmissibly reduce the voltage in the load unit. As a result, based on the system of equations of an asynchronous machine, the dependence of its reactive power on the supply voltage of the network was derived. The mathematical properties of this function are investigated with a physical justification of its unimodality and the presence of a minimum point. The obtained expressions make it possible to determine the magnitude of the control action on the high-speed reactive power compensation devices to stabilize the voltage level in the power supply unit.

Novel Features for Binary Time Series Based on Branch Length Similarity Entropy

Branch length similarity (BLS) entropy is defined in a network consisting of a single node and branches. In this study, we mapped the binary time-series signal to the circumference of the time circle so that the BLS entropy can be calculated for the binary time-series. We obtained the BLS entropy values for “1” signals on the time circle. The set of values are the BLS entropy profile. We selected the local maximum (minimum) point, slope, and inflection point of the entropy profile as the characteristic features of the binary time-series and investigated and explored their significance. The local maximum (minimum) point indicates the time at which the rate of change in the signal density becomes zero. The slope and inflection points correspond to the degree of change in the signal density and the time at which the signal density changes occur, respectively. Moreover, we show that the characteristic features can be widely used in binary time-series analysis by characterizing the movement trajectory of Caenorhabditis elegans. We also mention the problems that need to be explored mathematically in relation to the features and propose candidates for additional features based on the BLS entropy profile.

On Local Convergence of Stochastic Global Optimization Algorithms

In engineering optimization with continuous variables, the use of Stochastic Global Optimization (SGO) algorithms is popular due to the easy availability of codes. All algorithms have a global and local search character, where the global behaviour tries to avoid getting trapped in local optima and the local behaviour intends to reach the lowest objective function values. As the algorithm parameter set includes a final convergence criterion, the algorithm might be running for a while around a reached minimum point. Our question deals with the local search behaviour after the algorithm reached the final stage. How fast do practical SGO algorithms actually converge to the minimum point? To investigate this question, we run implementations of well known SGO algorithms in a final local phase stage.

Modified projected Newton scheme for non-convex function with simple constraints

In this paper, a descent line search scheme is proposed to find a local minimum point of a non-convex optimization problem with simple constraints. The idea ensures that the scheme escapes the saddle points and finally settles for a local minimum point of the non-convex optimization problem. A positive definite scaling matrix for the proposed scheme is formed through symmetric indefinite matrix factorization of the Hessian matrix of the objective function at each iteration. A numerical illustration is provided, and the global convergence of the scheme is also justified.

Reducing labor intensity when computing optimal technical characteristics of aerial ropeways

The article develops a procedure for optimizing the technical characteristics of ropeways - the step and the height of intermediate towers, and carrying ropes tension force. The optimization problem was based on the minimization of the tower structures cost. The reduction of computing labor intensity is based on the fact that the position of the minimum point of the objective function will be tied to one of the optimization restrictions. This allowed us to propose two ways to reduce the labor intensity of computing: a) reduction in the dimension of the optimization problem; b) replacement of the search for the minimum of the objective function with the solution of the nonlinear algebraic equation. The article shows that the proposed algorithm has increased computational efficiency. The algorithm allows us to obtain the same optimal values of technical characteristics of ropeways as in the solution of the previously developed optimization task but using simpler mathematical methods.