Value Of Critical Point Research Articles

The bus selection based on PV curve for the photovoltaic integration into power grid

Thanks to cost reduction, efficiency improvement, and fast advancement in power electronics, renewable energy, particularly solar power is increasing exponentially in the global energy sector. On the one hand, the integration of solar energy into the electricity is subject to a number of technical and non-technical challenges. Technical challenges include uncertainty of output power, system stability, imbalance between supply and demand, lack of reactive power, harmonics, angular stability, etc. The non-technical challenges include environmental, social and economic issues. On the other hand, the voltage profile in the weak nodes of the system is improved by the integration of solar power. The main purpose of the work is to identify buses which are suitable for the solar plant integration in the Albanian Power System (APS) based on the Power – Voltage (PV) curve method. The APS is modelled as an 18-bus grid (220 kV and 400 kV). The system simulation has been performed in the software PSS/E. Based on the critical point values of the PV curves methodology, two buses are identified as the most suitable for solar plant integration in the applications.

Pengaruh Kualitas Pelayanan dan Kompetensi Pegawai Terhadap Kepuasan Pengguna Jasa Pada Dinas Pemberdayaan Masyarakat dan Desa Kabupaten Katingan

The Community and Village Empowerment Service is the implementing element of Government Affairs in the Community and Village Empowerment Sector which is the regional authority. Implementation of the duties and functions of the Community and Village Empowerment Service as the Implementer of Local Government in the field of Community and Village Empowerment, various efforts have been made by the Leaders, starting from the Staff, Head of Section, Head of Division to the Head of the Katingan Regency Village Community Empowerment Service to spur service and competency improvements. However, all of this has not produced results or has a significant effect on improving employee services. This may be due to a complete lack of competence on how to improve employee services. The problems are as follows: 1) The quality of service is still low at the Katingan Regency Community and Village Empowerment Service. 2). Employee competence is still low in carrying out tasks/jobs at the Community and Village Empowerment Service. 3) Low employee work discipline can be seen from the inaccuracy of employees in using working hours and the absence of attendance (presence) which results in employees not being on time when leaving and coming home from work. This research aims are: 1). To analyze the effect of service quality on service users at the Katingan Regency Community and Village Empowerment Service. 2). To analyze the effect of employee competence on service user satisfaction at the Katingan Regency Community and Village Empowerment Service. This study uses a survey with a research instrument in the form of a questionnaire distributed to respondents. In collecting questionnaires through the process, researchers in collecting primary data with survey methods through research instruments (questionnaires) of all village governments in Katingan Regency with a research sample of 115 respondents. The research site is in Katingan Regency. Primary and secondary data sources, data collection methods used literature study (documentation), and questionnaires. The analytical tool used in this study is the PLS (partial least square) based SEM (structure equation model) method. The results of this study indicate that: The results of testing the effect of service quality on increasing service user satisfaction can be proven by looking at the estimated path coefficient value of 0.115 with a critical point value (t-statistic) of 0.618 (<1.96) or a P-value of 0.000 greater than = 0.05 which means it is not significant. The results of testing the effect of competence on increasing service user satisfaction can be proven by looking at the estimated path coefficient value of 0.763 with a critical point value (t-statistic) of 4.271 (> 1.96) or P-value 0.000 smaller than = 0.05 which means significant.

Theoretical investigation into the deciphering effects of atomic electronegativity on 2‐hydroxy‐phenyl‐tafamidis: A time‐dependent density functional theory study

AbstractIn light of the potential probe applications of 2‐hydroxy‐phenyl‐tafamidis (2HPT) and its derivatives with different atomic electronegativity (2HPT‐O, 2HPT‐S, and 2HPT‐Se), the mechanisms of excited state intramolecular proton transfer (ESIPT) of 2HPT derivatives have been investigated in this work. Via probing into the geometric parameters of hydrogen bond O‐H···N, infrared vibrational spectroscopy, and bond critical point values, we can confirm that hydrogen bonding is enhanced in the first excited state (S1). It is worth mentioning that the enhancement of hydrogen bonding in the S1 state by low atomic electronegativity 2HPT‐Se is particularly important. In light‐induced excitation, by comparing the changed behaviors of highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) orbitals, it could be found that photo‐induced charge transfer happens in excited molecules, and charge redistribution facilitates ESIPT reaction. Particularly, the low atomic electronegativity could promote the ESIPT process for 2HPT system. In order to clarify the detailed ESIPT mechanism, we construct the potential energy curves, search for the transition state form, and determine the ESIPT mechanism for 2HPT fluorophores. In this work, we not only elucidated the excited state behavior of 2HPT systems but also proposed a novel mechanism for regulating ESIPT by atomic electronegativity.

Reliability analysis of a new family mixed shock models for the multi-state systems

In this article, we introduce a new family of mixed shock models. Consider a system whose efficiency is k and the system is affected by r types of shocks, when the efficiency of the system reduces by one unit, regarding the occurrence of each one of the shocks. If K1 shocks of type I, K2 shocks of type II, …, Kr shocks of type r occur, in which K1+K2+…+Kr=k, the system loses its efficiency and fails. The system lifetime reliability function, the reliability of system lifetime in a perfectly functioning state, the reliability of system lifetime in partially working states, and the Laplace transformation of system lifetime have been calculated. In the following, the effect of critical point values on the reliability function of the system lifetime has been studied by using the simulation.

Design of automatic control system on trickle irrigation for tomato cultivation

The development of technology has had an impact on the progress of irrigation systems, called the intelligent irrigation system 4.0. The objectives of this research are a measurement of Emission Uniformity (EU) and designing automatic irrigation based on soil water sensors. The result of EU value is in the range of 85-90%, which is a good category. EU value can determine whether one emitter can represent the entire emitter in one irrigation system. The principle of the soil water sensor is to read the value of the soil moisture content in the planting medium. The soil water content of 22.4%, which is the field capacity, is used as an upper limit and the soil water content of 21.1%, which is the critical point, is used as the lower limit. Determination of the critical point value is done by using the management allowable depletion (MAD) value of 0.52. The working principle of the control system is to monitor the work of the soil water sensor and become the main data to control valves, pumps, and dosing. The required cost for the automatic system is Rp. 12,626,000, -.

E-Commerce Credit Network Control Strategy from a Critical Perspective

Credit problems are the main bottleneck in the development of e-commerce. Both the time and degree of e-commerce credit control directly affect its economic benefits. From the perspective of the criticality of complex systems, this paper explores the control node of e-commerce credit behaviour. Implementing control in this node can not only ensure the stable development of the credit network but also optimise the control cost. This paper constructs a credit behaviour model for the four regulatory behaviours of the transaction subject, analyses the evolution law of the credit network, and determines the critical state of the network. Finally, the paper’s empirical analysis and simulation experiments prove that when the false information in the credit network in the empirical data is 32%, the implementation of credit control has an efficient control effect. Nevertheless, 32% is not a universal result; the specific critical point value needs to be recalculated according to the theoretical derivation of the critical point combined with the actual network. These research results can help regulators obtain the highest regulatory return with the lowest regulatory investment.

Long-range order and quantum criticality in antiferromagnetic chains with long-range staggered interactions.

We study quantum phase transitions in Heisenberg antiferromagnetic chains with a staggered power-law decaying long-range interactions. Employing the density-matrix renormalization group (DMRG) algorithm and the fidelity susceptibility as the criticality measure, we establish more accurate values of quantum critical points than the results obtained from the spin-wave approximation, quantum Monte Carlo, and DMRG in literatures. The deviation is especially evident for strong long-range interactions. We extend isotropic long-range interactions to the anisotropic cases and find that kaleidoscope of quantum phases emerge from the interplay of anisotropy of the long-range exchange interaction and symmetry breaking. We demonstrate nonfrustrating long-range interactions induce the true long-range order in Heisenberg antiferromagnetic chains with a continuous symmetry breaking, lifting the restrictions imposed by the Mermin-Wagner theorem.

Critical temperatures of concrete-filled steel tubular columns for early-warning of fire-induced failure

The collapses of building structures in fire have occurred several times during the last two decades. To save lives from the collapsed building, a reasonable method is to predict the collapse of the structure in advance, for being able to evacuate the persons on site, such as fire-fighters, before the deadly collapse will occur. Therefore, in fire condition, the early-warning of structural collapse or member failure based on accurate on-site data collection and refined failure state determination is becoming a key issue in the fire research field. A parameter measured easily - the temperature - is taken as the indicator of the fire-induced failure, and an investigation on the refined critical temperatures of the concrete filled steel tubular (CFST) columns will be described in this paper. A series of fire resistance tests on CFST columns were conducted and are reported in this paper, and the influence of different test parameters, including column load ratio (0.3, 0.4 and 0.6), section type (circular and square sections) and fire scenario (fire exposure on two surfaces and all around the column), on the critical temperatures of CFST columns are discussed. Based on the test data and validated finite element analysis (FEA) models, refined critical temperatures (RCTs) for CFST columns were defined and are discussed. Compared with the traditional critical temperature, the RCTs clearly defined the positions and values of critical temperature points, which makes it applicable to be used as the early-warning of fire-induced failure of CFST columns.

STUDI EKSPERIMENTAL PERFORMANCE KAVITASI WATERJET PROPULSI

Cavitation is a complex phenomenon of dynamic processes in hydraulic machines that can cause a decrease in energy performance, vibration and damage the blade surfaces. Analysis of cavitation symptoms in hydraulic machines is carried out through cavitation performance studies, namely the relations between energy parameters. Each hydraulic machine has a critical value on a different cavitation performance curve. Therefore, a study of the effect of cavitation changes is needed to determine the working zone of hydraulic machines without cavitation. In this study, cavitation performance analysis was carried out on a waterjet propulsor model with 5 impeller blades and 7 stator blades using experimental methods. The cavitation coefficient was varied at σ = 2.25 to 0.25 by setting and controlling the inlet pressure on the cavitation test rig. The critical point value will be observed at the point where the thrust coefficient decreased to 3.28%. The results showed that cavitation begins at σ = 1, the critical point is obtained at σ = 0.75. From these studies, we find that waterjet must be operated at conditions where is σ > 0.75.

Study on Molecular Dynamics of Singular Nature of Physical Properties near Critical Point in Carbon Dioxide System

Based on the molecular dynamics simulations, this paper analyzed the singular nature of physical properties of the carbon dioxide near the critical point. Detailed analysis of density simulation exhibited that an excellent agreement can be obtained by COMPASS forcefield besides the pseudo-critical region, while the peculiar behavior of density can again be observed. The computational domain is divided into the small sub-domains in which the standard deviation are evaluated as density fluctuation, and it shows maximum near the critical point and higher values at supercritical condition than that at subcritical condition. A new 3-parameter model was put forward to define the CO2 dimer distribution after each molecule in the domain had been supplied with the local coordination frame. The result shows that the T-shaped dimer is with higher probability to be formed than the parallel and crossed configuration, and the conversion of these dimer conformations closely associates with the peculiar properties of the critical point.

Investigating cyclic cooperativity in ring stabilization of (HCN)n and (HNC)n: n = 3–11 clusters

The cooperativity effect in cyclic molecular clusters of hydrogen cyanide (HCN) and its isomeric form hydrogen isocyanide (HNC) is studied in the present work. The cyclic ring stabilization and molecular cooperativity of the (HCN)n and (HNC)n clusters n = 3 to 11 are studied as example with DFT method at B3LYP/6-31G(d,p) level of theory. The observed cyclic cooperativity increases with clusters size. Remarkable correlation between cyclic cooperativity energy (CCE) and hydrogen bond density critical point value (ρBCP) of the clusters is observed with molecular electron density (MED) topography. Higher cooperativity is observed in (HCN)n clusters than the respective (HNC)n ones.

Design of Hybrid Recommendation Algorithm Based on User Dynamic Behavior and Static Attributes

Collaborative filtering recommendation algorithm is one of the most successful recommendation algorithms, but the traditional collaborative filtering recommendation algorithm is proved to have a series of problems in data sparsity, cold boot and scalability. Based on the problems mentioned above, this paper analyses user dynamic behavior and a hybrid recommendation algorithm based on user dynamic behavior and static attributes (UDBSA) was proposed in this paper. By determining the optimal value of BP critical point for the number of ratings, the recommendation strategy was dynamically selected according to the number of ratings. This method can comprehensively alleviate the influence of problems of new users and concept drift related problem on recommendation results.

Influence of inhibitory synapses on the criticality of excitable neuronal networks

In this work, we study the dynamic range of a neuronal network of excitable neurons with excitatory and inhibitory synapses. We obtain an analytical expression for the critical point as a function of the excitatory and inhibitory synaptic intensities. We also determine an analytical expression that gives the critical point value in which the maximal dynamic range occurs. Depending on the mean connection degree and coupl\-ing weights, the critical points can exhibit ceasing or ceaseless dynamics. However, the dynamic range is equal in both cases. We observe that the external stimulus mask some effects of self-sustained activity (ceaseless dynamic) in the region where the dynamic range is calculated. In these regions, the firing rate is the same for ceaseless dynamics and ceasing activity. Furthermore, we verify that excitatory and inhibitory inputs are approximately equal for a network with a large number of connections, showing excitatory-inhibitory balance as reported experimentally.

The Bioactive Potential of Functional Products and Bioavailability of Phenolic Compounds.

The expression of bioactivity depends on the assimilation of different classes of natural substances (e.g., phenolic compounds) in vivo. Six functional extracts (Aspalathus linearis, leaves; Paullinia cupana, seeds; Aristotelia chilensis, berries; Ilex paraguariensis, leaves; Syzygium aromaticum, cloves, and wild berries) were analyzed in vitro and in vivo as an alternative to alleviating pathologies associated with oxidative stress (proliferation of cancer cells). The purpose of this research was to evaluate the in vitro and in vivo antioxidant and cytotoxic potential of hydroalcoholic solutions, in addition to the assimilation capacity of bioactive components in Saccharomyces boulardii cells. In vivo antioxidant capacity (critical point value) was correlated with the assimilation ratio of functional compounds. The results of in vitro antioxidant activities were correlated with the presence of quercetin (4.67 ± 0.27 mg/100 mL) and chlorogenic acid (14.38 ± 0.29 mg/100 mL) in I. paraguariensis. Bioassimilation of the main nutraceutical components depended on the individual sample. Phenolic acid levels revealed the poor assimilation of the main components, which could be associated with cell viability to oxidative stress.

Stability Analysis of Casson Nanofluid Flow over an Extending/Contracting Wedge and Stagnation Point

This numerical study is conducted to scrutinize the dual solutions and stability analysis of the flow of Casson nanofluid past a permeable extending/contracting wedge and stagnation point. Momentum, heat and mass transfer behaviors of the Casson nanofluid have been modeled with the use of the Buongiorno nanofluid model. Suitable self-similarity variables are employed to convert the fluid transport equations into ordinary differential equations and the bvp4c MATLAB solver is used to solve the equations. The impacts of active parameters on fluid transport properties are illustrated graphically. The outcomes of the present analysis reveal that the influence of Casson fluid parameter on velocity and temperature distributions obtained from the first and second solutions exhibit the opposite natures. From the stability analysis, it is found that the thermophoresis and Brownian motion effects acquire the same critical point value on Nusselt number. The temperature distribution of the Casson nanofluid is higher over the wedge than stagnation point. The two solutions are found for the limited range of extending/contracting parameter. The detailed stability test is carried out to determine which of the two solutions is physically realizable and stable.

Effects of quantum statistics near the critical point of nuclear matter

Effects of quantum statistics for nuclear matter equation of state are analyzed in terms of the recently proposed quantum van der Waals model. The system pressure is expanded over a small parameter $\delta \propto n(mT)^{-3/2}[g(1-bn)]^{-1}$, where $n$ and $T$ are, respectively, the particle number density and temperature, $m$ and $g$ the particle mass and degeneracy factor. The parameter $b$ corresponds to the van der Waals excluded volume. The corrections due to quantum statistics for the critical point values of $T_c$, $n_c$, and the critical pressure $P_c$ are found within the linear and quadratic orders over $\delta $. These approximate analytical results appear to be in a good agreement with exact numerical calculations in the quantum van der Waals model for interacting Fermi particles: the symmetric nuclear matter ($g=4$) and the pure neutron matter ($g=2$). They can be also applied to the system of interacting Bose particles like the matter composed of $\alpha$ nuclei.

Structure Diagnostic of Iron-Based Out-of-Peritectic Alloys during Nonequilibrium Crystallization

The effect of the contribution of basic components (silicon, manganese, chromium, and nickel) in multicomponent iron-based alloys on critical point position of the peritectic reaction was studied by using the POLYTHERM software package. Obtained temperature and concentration values of critical points of peritectic transformation, depending on the content of iron-based alloy components (Si, Mn, Cr, Ni) were used to build summary equations, represented the change in temperature and concentration of critical points by variation of binary, ternary and quaternary alloy composition. Investigation of nonequilibrium crystallization of out-of-peritectic casting steels was performed by using a system of computer models describing thermodynamic, thermophysical, diffusion and capillary processes during solidification under coalescence of dendritic branches. The nonequilibrium crystallization regime was specified by suppression of diffusion in the solid phase, reflected by adding the inverse diffusion parameter to the system of the computer model. The application of these computer models not only allows to make calculations of the temperature course, the solid phase fraction and the composition of the components in the liquid phase but also the calculation of secondary arm spacing during crystallization with taking into account the coalescence process.

The Effect of Resins on Rheological and ageing Characteristics of Bitumen for Pavement

Bitumen consists of thousands of hydrocarbon molecule types with each molecule contributes to the overall bitumen characteristics. Therefore, it is important to identify the influence of each chemical component of bitumen that altogether constructs the bitumen characteristics. This is likely to be completed by evaluating and modifying bitumen components to produce a new type of bitumen with better characteristics. The realistic way to do this is by analysing it in groups or fractions; one group or fraction comprises bitumen molecules with similar characteristics. This paper aims to address this issue by describing the effect of resins on rheological characteristics of bitumen at various ageing process stages. The materials used in this study were Buton rock asphalt or natural rock asphalt from Buton Island in Indonesia which was from Lawele region and petroleum bitumen penetration grade 80/100 from a refinery in Kemaman Malaysia. The materials were tested to identify their charactheristics and the resins components were also extracted and tested with Corbett method. Each extracted resin (from Buton rock asphalt bitumen and petroleum bitumen) was blended in proportions of 0%, 5%, and 10% with the Kemaman petroleum bitumen as a bitumen medium. The blended bitumen samples were also tested for their rheological characteristics using Dynamic Shear Rheometer. Each sample was tested at five different temperature levels (46°C, 52°C, 58°C, 64°C and 70°C) and at un-aged, artificial short-term aged (RTFOT-aged), and artificial long-term aged (PAV-aged) conditions. The results indicated that the source of resins had a significant value of 0.065 or larger than the 0.05 critical point value. There was no difference in the effect of the experiments using either Buton rock asphalt or petroleum bitumen on the complex shear modulus G*. At fresh condition, there was no effect of adding resins on the bitumen rheological characteristics except for the elastic modulus (G’). However, the effect increased over the RTFOT-ageing and PAV-aging level because of the normal ageing process.

Using fractal analysis methods in studying mechanisms of deformation and destruction of nano-modified cement concretes

The research results for the mechanism of deformation and destruction of nano-modified fibre-reinforced fine-grained cement concretes are given. Multi-layer polyhedral carbon structures (astralenes) were used as a nano-modifying additive in the formulation of concrete mixtures, which were injected into cement systems together with hard vehicles in the form of basalt micro-fibres. The influence of three types of mineral additives (condensed compacted microsilica, highly active white metakaolin and sulfoaluminate additive 'Penetron Admix') on physical and mechanical properties of dispersive reinforced fine cement concretes under study have been identified. Using the minimal coverage method, quantitative values of critical points have been identified on deformation curves of cement concretes in compression characterising the accumulation moment within fibre-reinforced fine-grained cement concretes for a specific level of micro-defects causing first cracks to occur. It has been found that fibre-reinforced nano-modified fine-grained cement concrete containing highly active white metakaolin as a mineral additive in the amount of 6% of the Portland cement weight has the highest physical and mechanical properties.

Phase Equilibrium and Critical Phenomena in the n-Pentan–Water and n-Hexane–Water Systems at High Temperatures and Pressures

PVTx-properties of the H2O – n-C5H12 and H2O – n-C6H14 mixtures are measured in the temperature range 303-680 K at pressures up to 60 MPa. The measurements were carried out along 265 liquid and vapor isochors in a density range of 63-713 kg/m3. The measurements were performed for 15 concentrations between 0.110 and 0.987 mole fractions of H2O for the C5H12 mixtures and for 11 concentrations between 0.166 and 0.977 mole fractions of H2O for the C6H14 mixtures. The temperatures and pressures on the three-phase and two-phase boundary curves were obtained for the mixtures from isochors using the kink or inflection method. The data for the critical parameters of the upper and lower branches of the critical curves were obtained from the boundary curves by the method of rectilinear diameter. The measured three-phase data were used to estimate the value of the upper final critical point.