Fundamental Analyses Research Articles

Comparison Random Forest Regression and Linear Regression For Forecasting BBCA Stock Price

Stock trading is a popular financial instrument worldwide. In Indonesia, the stock market is known as the Indonesia Stock Exchange (BEI), and one actively traded stock is PT Bank Central Asia (BBCA). However, predicting stock price movements is challenging due to various influencing factors. Investors use fundamental and technical analyses for decision-making, but results often vary. Machine learning, particularly random forest regression and linear regression algorithms, can be used for stock price forecasting. In this paper, we compares these two machine learning methods to forecast BBCA stock prices, aiming to provide more accurate and effective solutions for investor's investment and trading decisions. The evaluation results of cross-validation mean squared error (MSE), root mean squared error (RMSE), mean absolute error (MAE), and mean absolute percentage error (MAPE) for linear regression were 0.12848, 0.35807, 0.29570, and 0.0036%, respectively, while for random forest regression were 27473.76, 158.04, 142.70, and 1.7153%. These findings indicate that linear regression outperforms in forecasting performance.

Model-Free Sliding Mode Enhanced Proportional, Integral, and Derivative (SMPID) Control

This study proposes a type of Sliding Mode-based Proportional, Integral, and Derivative (SMPID) controllers to establish a model-free (treat dynamic plants as a whole uncertainty) sliding model control (MFSMC) platform for Bounded-Input and Bounded-Output (BIBO) dynamic systems. The SMPID design (1) proposes a sliding mode error (rather than error) as the PID input, (2) directly links to Lyapunov asymptotic stability to provide total robust nonlinear dynamic inversion (NDI), and (3) reduces the chattering effects in terms of Lyapunov definite positive stability. Further, the study proposes a general SMC framework to accommodate asymptotic time stabilisation and finite-time stabilisation for both model-based and model-free designs. A U-control framework is presented to integrate the SMPID control (for NDI) and an invariant control (IC) (for specifying the whole control system’s dynamic and static responses), which significantly relaxes the PID tunings and generates the specified performance. To provide assurance and guidance for applications and expansions, this study presents the relevant fundamental analyses and transparent simulated bench tests. It should be noted that the new SMPID in forms of u=SMPID(σ(e))=PID(sliding-mode) is different from that studied u=sliding-mode(PID(e)) in expression and functionality.

A numerical method to calculate screening current-dependent self and mutual inductances of REBCO coils

The screening current and its relaxation cause the variation of the self- and mutual inductances of REBCO coils—REBCO is one of the high-temperature superconductors. However, most studies of coil voltage analysis on a REBCO magnet, a stack of coils, have reported simulation results assuming invariant self- and mutual inductances so far. Although the conventional assumption of invariant inductances is still acceptable for fundamental coil voltage analyses, it can cause misleading conclusions due to inductive voltage errors when a precise coil voltage analysis is demanded. Hence, here we report a numerical method to calculate screening-current-dependent self- and mutual inductances of REBCO coils for advanced studies based on a lumped-circuit analysis model. In this work, we aim to investigate the inductance variation due to the screening current with a case study and discuss its effects on the coil voltage. We assume that there is a stack of 12 REBCO single-pancake coils. No transverse current in each coil is considered for simplicity. A numerical simulation of the current density in the magnet is performed, and then the inductances are calculated by considering the spatially non-uniform current density due to the screening current. From this case study, we confirm that the self- and mutual inductances are changed by up to 110% and 30% each. It is also confirmed that the discrepancy is notable at the beginning of the charge while marginal at the end. Finally, we discuss the effect of inductance variation on the quench voltage analysis.

Proposing empirical correlations and optimization of [formula omitted] and [formula omitted] of nanofluids in channels and predicting them using artificial neural network

Getting the best performance from a thermal system requires two fundamental analyses, energy and entropy generation. An ideal mechanism has the highest Nu and the lowest entropy Sgen. As part of this research, a large dataset of fluid flow via tubes has been collected experimentally. As well as the inclusion of nanoparticles, analyses are included as well. By using deep learning algorithms, the Nusselt number and total entropy generation are predicted. In both models, the mean absolute error was lower than 5%. To determine the most accurate model, hyperparameter tuning is performed. That is adjusting all the settings in the neural network to attain the best results. The results of the predictive models are compared against experimental and benchmark results. The study incorporates a massive optimization strategy to fine-tune the predictive capabilities of the models. Furthermore, the model's predictive abilities are evaluated through the use of the coefficient of determination R2. For water and nanofluids flowing through circular, square, and rectangular cross-sections, the proposed models can predict Nu and Sgen. The results showed remarkable agreement with the experimental results. The models showed an MAE of not higher than 1.33%, which is a great achievement. Also, empirical correlations are proposed for both parameters, and double factorial optimization is implemented. The results showed that to achieve the best results, the Re should be higher than 1600, and the nanoparticle concentration should be 3%. A thorough justification of selected cases is presented as well.

Mapping Human Neuronal Diversity in the Search for New Therapeutics: Using Real Human Neuron Data Sets to Build Student Quantitative Skills.

Case studies are a high impact educational practice that engage students in collaborative problem solving through storytelling. HITS, an NSF funded research coordination network dedicated to exposing students to high-throughput discovery science, drove creation of this case. In this case, students imagine themselves as researchers developing new therapeutic drugs for epilepsy. Specifically, students work with the Allen Cell Types Database, which is the result of collaborative, interdisciplinary open science. Neurosurgeons partnered with the Allen institute to provide living human brain tissue for electrophysiological, morphological, and transcriptomic study. Students collaborate to collect and organize data, investigate a research question they identified, and perform fundamental statistical analyses to address their question. By leveraging the unique Cell Types dataset the case enhances student knowledge of epilepsy, illuminates high-throughput scientific approaches, and builds quantitative and research related skills. The case is also versatile and was implemented in two distinct courses. The case can also be taught in different modalities, in person or remote, with a combination of synchronous and asynchronous work. Indirect and direct measures along with quantitative and qualitative approaches were used for case assessment and improvement. Students performed well on case related exam questions, reported high confidence in their achievement of the learning outcomes, and enjoyed the case's link to neurological disease, real research data and advanced technological approaches. Our assessment findings and instructor implementation experiences are also included to facilitate the adoption or adaptation of the case for a variety of courses and/or modalities in neuroscience and STEM related curricula.

Analysis Stock Price Comparison with Price To Book Value (PBV) Method as the Basis for Investment Decisions At Starup Indonesia Company

The research is motivated by the antuasias of the Indonesian people who want to invest today, especially in the era of digitalization, it is so easy to be able to make stock buying and selling transactions. Moreover, it is supported by the rise of starup issuers that have been listed on the Indonesia Stock Exchange. The purpose of this study provides an overview of fundamental stock analysis using the 2021 Price To Book Value (PBV) method in companies with the starup logo in Indonesia as the basis for investment decisions for investors or potential investors. This research method is quantitative descriptive, where there are 9 starup companies that have entered the capital market from 2017-2021. The results of this study show that of all starup issuers there are four issuers, namely PT Yelooo Integra Datanet Tbk., PT Yelooo Integra Datanet Tbk., PT Yelooo Integra Datanet Tbk., and PT Bukalapak.com Tbk. which are still in low stock prices. Meanwhile, the other 5 issuers stated that the stock price was quite expensive. Furthermore, all issuers are eligible as an option to invest, where only the issuer of PT Yelooo Integra Datanet Tbk. has an undervalued position, where the market price is lower than its book value. The rest are in an overvalued position, where the market price is higher than the book value. PBV analysis is one of the fundamental analyses that can be used as a basis for investment considerations, it is expected for investors or potential investors and other researchers to be able to use other analyses such as Price Earning Ratio (PER), Return On Equity (ROE), Devident Payout Ratio (DPR) and others as a basis for making investment decisions, especially in the long term

Pivotal Routes for Maximizing Semitransparent Perovskite Solar Cell Performance: Photon Propagation Management and Carrier Kinetics Regulation.

Semitransparent perovskite solar cells (ST-PSCs) are ideal candidates for building-integrated photovoltaics (BIPV) and tandem solar cells (TSCs) owing to their tunable bandgap and high visible transparency. The best power conversion efficiency (PCE) of ST-PSCs is close to 15% with an average visible transmittance of over 20%, which still lags far behind the PCE of normal opaque PSCs. This can be attributed to the poor light utilization efficiency (LUE) of ST-PSCs. Herein, the pivotal routes for maximizing LUE of ST-PSCs in terms of photon propagation management and carrier kinetics regulation are systematically rationalized. First, the fundamental theoretical analyses on optical processes and electronic properties are provided. Then, insights on photon propagation management measures and carrier kinetics regulation strategies are provided. Furthermore, a summary of the promising commercial application of ST-PSCs in BIPV and TSCs is provided. Finally, the main progress of ST-PSCs is briefly summarized, and the directions for the commercialization of ST-PSCs are proposed.

Synthesis and characterization of a novel collector for the desulfurization of fine high-sulfur bauxite via reverse flotation

Bauxite is one of the main raw materials in the alumina industry. Fine high-sulfur bauxite flotation desulfurization is a great challenge presently. This study aims to synthesize nanoparticle collectors (NPCs) by emulsion polymerization to improve the abovesaid flotation desulfurization process. The physicochemical properties of high-sulfur bauxite were analyzed, and the experimental conditions for the synthesis of NPCs were optimized. The interaction mechanism between NPCs and pyrite was studied via fundamental analyses including SEM (Scanning Electron Microscope), FT-IR (Fourier Transform Infrared spectoscopy), Zeta-potential, XPS (X-ray Photoelectron Spectroscopy), and wettability. Under the closed-circuit flotation flowsheet of “one roughing-two cleaning-three scavenging”, aluminum concentrate with a yield of 85.91% and sulfur content of 0.56% were obtained using a common collector. However, with the addition of the novel NPC, aluminum concentrate with a yield of 85.70% and sulfur content of 0.36% could be obtained by a simpler flowsheet of “one roughing-one cleaning-two scavenging”. The improvement in flotation performance is suggested to be contributed by the addition of spherical NPC, which induced a rougher and more hydrophobic pyrite surface.

On the Fundamental Analyses of Solutions to Nonlinear Integro-Differential Equations of the Second Order

In this article, a scalar nonlinear integro-differential equation of second order and a non-linear system of integro-differential equations with infinite delays are considered. Qualitative properties of solutions called the global asymptotic stability, integrability and boundedness of solutions of the second-order scalar nonlinear integro-differential equation and the nonlinear system of nonlinear integro-differential equations with infinite delays are discussed. In the article, new explicit qualitative conditions are presented for solutions of both the second-order scalar nonlinear integro-differential equations with infinite delay and the nonlinear system of integro-differential equations with infinite delay. The proofs of the main results of the article are based on two new Lyapunov–Krasovskiĭ functionals. In particular cases, the results of the article are illustrated with three numerical examples, and connections to known tests are discussed. The main novelty and originality of this article are that the considered integro-differential equation and system of integro-differential equations with infinite delays are new mathematical models, the main six qualitative results given are also new.

Computational Catalyst Design for Dry Reforming of Methane: A Review

Because of the recent global warming environmental issues, dry reforming of methane (DRM)─which converts greenhouse gases (CO2 and CH4) into syngases (CO and H2)─is receiving significant attention. Recently, density functional theory (DFT) calculations have been effectively used to obtain fundamental information on DRM reactions. The DFT calculations can provide valuable theoretical knowledge in various heterogeneous catalyst systems, which is difficult to derive from experiments alone due to the complexity of reaction pathways. This work introduces theoretical studies concerning the most plausible reaction pathways, catalytic activities, and stabilities of Ni- and non-Ni-based metal catalysts. The review includes fundamental analyses of reaction mechanisms, catalytic activities, and several strategies to improve the catalytic properties of Ni- and non-Ni-based catalysts. Such strategies include doping, introducing promoters, forming bimetallics, and utilizing various catalyst supports. In addition, DFT-based descriptors provide guidelines for DRM catalyst design in terms of activity and stability. In conclusion, this review also suggests DFT-based analyses of catalysts based on morphological and compositional engineering, such as core–shell nanoparticles, single-atom catalysts, phosphides, and reduced solid solution catalysts. Finally, this review suggests a rational catalyst design for DRM by tuning catalytic properties based on engineered catalyst characteristics under a comprehensive understanding provided by DFT calculations and experiments.

Identifying Parameters for Defining "Essentially Derived Varieties" of Maize Inbred Lines Using High-Throughput Genome-Wide SNP Markers.

Well-developed maize reference genomes and genotyping technology along with fast decreasing detection costs have enabled the chance of shifting essentially derived varieties (EDV) identification to high-throughput SNP genotyping technology. However, attempts of using high-throughput technologies such as SNP array on EDV identification and the essential baseline parameters such as genetic homozygosity and/or stability in EDV practices have not been characterized. Here, we selected 28 accessions of 21 classical maize inbreds, which definitely form a pedigree network from initial founders to derivatives that had made huge contribution to corn production, to demonstrate these fundamental analyses. Our data showed that average residual heterozygosity (RH) rate of these 28 accessions across genome was about 1.03%. However, the RH rate of some accessions was higher than 3%. In addition, some inbreds were found to have an overall RH rate lower than 2% but over 8% level at certain chromosomes. Genetic drift (GD) between two accessions from different years or breeding programs varied from 0.13% to 13.16%. Accessions with low GD level showed cluster distribution pattern and compared with RH distributions indicated that RH was not the only resource of GD. Both RH and GD data suggested that genetic purity analysis is an essential procedure before determining EDV. Eleven derivative lines were characterized with regard to their genome compositions and were inferred as their breeding histories. The backcross, bi-parental recycling, and mutation breeding records could be identified. The data provide insights of underlining fundamental parameters for defining EDV threshold and the results demonstrate the EDV identification process.

(Invited) Photoelectrochemical Energy Materials and Device

Nowadays, the exploration of new photoelectrode architectures to improve the light-harvesting and charge-collection properties of photoelectrochemical cells and related devices have been regarded as a challenging work. The efficient, stable, visible light absorption and cost effective photoelectrode materials are certainly important in developing highly efficient PEC system. Here, we synthesized the various metal oxide and nitrides for photoelectrochemical water splitting. Based on their synthesis methods and intrinsic properties, we tested the possibility(large-scale and stability) toward their PEC applications. Related deep insight would be discussed in terms of the fundamental analyses and reasonable results based on the theoretical background to give an meaningful potential for the future PEC world.

Inverse-cavity structure for low-threshold miniature lasers

Creating micro and nano lasers, high threshold gain is an inherent problem that have critically restricted their great technological potentials. Here, we propose an inverse-cavity laser structure where its threshold gain in the shortest-cavity regime is order-of-magnitude lower than the conventional cavity configurations. In the proposed structure, a resonant feedback mechanism efficiently transfers external optical gain to the cavity mode at a higher rate for a shorter cavity, hence resulting in the threshold gain reducing with decreasing cavity length in stark contrast to the conventional cavity structures. We provide a fundamental theory and rigorous numerical analyses confirming the feasibility of the proposed structure. Remarkably, the threshold gain reduces down by a factor ~ 10−3 for a vertical-cavity surface-emitting laser structure and ~ 0.17 for a lattice-plasmonic nanocavity structure. Therefore, the proposed approach may produce extremely efficient miniature lasers desirable for variety of applications potentially beyond the present limitations.

Comparison of the capillary-channeled polymer (C-CP) fiber spin-down tip approach to traditional methods for the isolation of extracellular vesicles from human urine.

Capillary-channeled polymer fiber (C-CP) solid-phase extraction tips have demonstrated the ability to produce clean and concentrated extracellular vesicle (EV) recoveries from human urine samples in the small EV size range (< 200nm). An organic modifier-assisted hydrophobic interaction chromatography (HIC) approach is applied in the spin-tip method under non-denaturing conditions-preserving the structure and bioactivity of the recovered vesicles. The C-CP tip method can employ either acetonitrile or glycerol as an elution modifier. The EV recoveries from the C-CP tip method (using both of these solvents) were compared to those obtained using the ultracentrifugation (UC) and polymer precipitation (exoEasy and ExoQuick) EV isolation methods for the same human urine specimen. The biophysical and quantitative characteristics of the recovered EVs using the five isolation methods were assessed based on concentration, size distribution, shape, tetraspanin surface marker protein content, and purity. In comparison to the traditionally used UC method and commercially available polymeric precipitation-based isolation kits, the C-CP tip introduces significant benefits with efficient (< 15min processing of 12 samples here) and low-cost (< $1 per tip) EV isolations, employing sample volumes (10 µL-1mL) and concentration (up to 4 × 1012 EVs mL-1) scales relevant for fundamental and clinical analyses. Recoveries of the target vesicles versus matrix proteins were far superior for the tip method versus the other approaches.

Noncovalent interactions: A brief account of a long history

AbstractThe history of noncovalent interactions is outlined, starting with early interpretations of the symmetry of crystals, then with the fast development of coordination chemistry, and of fundamental analyses in the last century. An attempt is made to provide for the practicing scientists who use noncovalent interactions a historical background of the field, paying credit to often forgotten predecessors. A separate section shows that only in the 20th century instrumentation provided a firm basis for the exploration of noncovalent interactions. Selected examples illustrate the early and rather accurate calculations of some noncovalent energies. With the advent of supramolecular chemistry, noncovalent interactions became a mainstream field of science; this allowed further insight into the nature and strength of these seemingly weak forces. Intermolecular interactions in biological systems have also received early attention. As far as possible, exact references are given for the original publications.

GICharm: A System Level Analysis Tool for Geomagnetic Disturbance Related Harmonics

Power systems can and have been impacted by harmonics generated during geomagnetic disturbances (GMD) events. These harmonics are generated from the part-cycle saturation of power transformers caused by the flow of geomagnetically-induced currents through grid-connected transformers. This article describes a system level harmonic analysis tool needed by the industry to perform an adequate assessment of GMD-related distortion impacts. When the results of a properly performed harmonic assessment are combined with the fundamental frequency analyses, a much more accurate evaluation of grid security during GMD can be obtained. The tool is publicly available for engineers, students, and researchers. It provides multiple examples, including a validation against published measurements from an experimental setup consisting of two back-to-back connected transformers in the Fingrid power network. Final of this article briefly discusses the results of that validation.

Cyberfeminism: A Relationship between Cyberspace, Technology, and the Internet

The current of cyberfeminism has been active for 30 years now, also referred to as the “third wave” of feminism. Despite being an ambiguous and multifaceted movement involving multiple instances, cyberfeminism is represented in the imagination by women with strong knowledge of media and digital technologies. The purpose of this article is to analyze the socially and culturally constructed value that the media assume in this movement. The very concept of identity is undergoing a phenomenon of control whereby it is redefined by “control grids” (D. Haraway) that prevent free access to participation in life on the web. The utopian theories of feminists actually alternate with fundamental gender analyses within cyberspace that determine the amount of access to resources. The last phase of this phenomenon is instead characterized by the intent to break down gender inequalities through a series of digital products that produce changes in common perceptions: online magazines, YouTube channels, webinars, and entrepreneurship actions on the web. New media and, more generally, access to information are fundamental to social and political participation, in which the phenomenon of exclusion or production of inequalities is more visible. Gender divisions on the web also reinforce sociocultural barriers and sometimes create regressive and destructive forms of social bonds. Globalization also affects these dynamics and accentuates exaggerated forms of individualism and cognitive stiffening, which further accentuate the distinctive traits of gender inequalities in cyberspace.

Management and Leadership in the Klang Valley IT Sector: Conceptual Approach

The aim is to conceptualize what makes for effective leadership in the Klang Valley IT sector. All industries need effective leadership; it ought to be brought up in the workplace. Employee motivation and performance could be improved through effective leadership. Additionally, employees are more committed to the organization, while lowers the turnover rate. Under successful leadership, an organization’s output and revenue can increase. The unethical behaviour by leaders who lack drive, confidence, foresight, and communication skills affects most industries. Perhaps these traits (ethics, motivation, trustworthiness, vision, and good communication) put things in perspective and provide direction as the author takes this challenging journey through a setting that only gets trickier as the person rises to the leadership level within the firm. This study will be able to improve leadership effectiveness through the issues’ goals. About 225 thousand people were working in the Malaysian IT sector. Each hypothesis has been observed and demonstrated. The substantial result was supported for each hypothesis from the previous study. In this instance, the conceptualized study has assessed and carried out fundamental analyses like descriptive, reliability, and validity analysis to determine how dependable the variables are for future research. The findings show that these dimensions (ethics, motivation, trust, vision, and good communication skills) are the essential elements of effective leadership. This study gave organizations and sectors reasons to raise employee levels of effective leadership to meet organizational goals and improve the attitudes and behaviours of leaders. Although there are many opportunities for exciting theoretical advancement and significant policy ramifications in this field of study, strict ethical guidelines must follow to have effective leadership quality in the IT sector. The novel aspect of this study is vision, which is a crucial element of the new leadership strategy. Followers and changes are prepared for their vision and are always necessary for this method.

Fundamental Analyses on Industrial Accidents in the Construction Industry

Fundamental Analyses on Industrial Accidents in the Construction Industry

Case Law Trends: The CJEU’s Approach to the Objectives of Progressive Turnover-Based Taxes: Respect for the Member States’ Fiscal Sovereignty or Authorization for Circumventing EU Law?

The article demonstrates that the objective of the tax system plays a crucial role in the non-discrimination assessment in the context of both EU State aid and fundamental freedoms analyses. Despite the fact that the objective of the underlying tax system/tax measure is decisive in respect of the outcome of these non-discrimination tests, there are plenty of uncertainties in the Court of Justice’s case law regarding the scrutiny of the objectives of tax measures. The article sheds light on them, first, by examining the allocation of competences among national authorities – national courts – and the EU adjudicatory bodies with regard to the determination of the objective of the tax system. Then, the required standard of consistency between the declared objective and the design of the tax system is scrutinized in the context of the recent progressive turnover-based tax cases, suggesting a stricter standard of consistency that is based on the principle of proportionality. The article also attempts to disentangle the blurred relationship between the objective of the tax and the intent of the legislator, and argues that the Court’s inquiry should not be directed at the legislature’s intent rather at the objective of the tax, as the former is difficult to identify. Finally, the question of abuse of rights by the Member States is discussed, that is, Member States can circumvent EU law by enacting seemingly neutral taxes the actual objective of which is to discriminate or selectively favour certain groups of taxpayers. Non-discrimination, state aid, fundamental freedoms, turnover-based taxes, objectives of tax measures, circumvention of law, abuse of rights, de facto selectivity, intention of legislature, progressive taxation.