Systematic Control Research Articles

An improved method for rapid and safe preparation and measurement of dimethylmercury using gas chromatography-atomic fluorescence spectrometry

Transformations between dimethylmercury (DMHg) and other mercury (Hg) species have been one of the critical knowledge gaps in the Hg global biogeochemical cycle due to the lack of detailed studies. The preparation and measurement of DMHg are challenging due to the high toxicity and volatility of DMHg. In this work, we invented a new DMHg generator for successfully preparing high-purity DMHg in a highly controllable and safe way. The DMHg could be spontaneously volatilized and diffused from the original preparation solution to the solution to be studied. The parameters for generating DMHg were optimized to be the pH value of 4.0 with a MeCo/Hg2+ molar ratio of 10 at 20 °C. The following measurement method of DMHg in the presence of various species of Hg was also investigated and optimized. Hg0 and DMHg could be separated effectively with the carrier gas flow rate of 15 mL min−1 and the gas chromatography column temperature of 30 °C. The interferences of Hg0, monomethylmercury and other species were excluded by systematic control experiments. A sensitive and reliable approach for quantifying trace DMHg in water was developed. Under the optimal conditions, the limits of detection for Hg0, MMHg and DMHg were 0.03, 0.002 and 0.024 ng L−1, respectively, with the relative standard deviation below 8.2%. The developed method was validated by the determination Hg species of different natural water samples. This work is expected to provide a new and safe strategy for DMHg preparation and a verified method for DMHg measurement.

Сравнительный анализ уровня специальной физической подготовки студентов элективного направления "Волейбол": до- и постпандемийный периоды

Systematic pedagogical control at all stages of the educational process is an important and mandatory component of the teacher's activity, without which effective management, evaluation of the effectiveness and efficiency of the pedagogical process is impossible. This year, this preliminary monitoring was an even more important task, since it was preceded by two years of distance learning, when all education was implemented in difficult remote conditions, which was a difficult task for the practice-oriented discipline "Physical Education", when it was not possible to fully develop physical qualities of students, and even more so to fully master motor actions. The purpose of the study is to compare and analyze the results of the level of special physical fitness (SPP) of female volleyball players in the pre- and post-pandemic periods. To achieve this goal, the following tasks were solved: to test the level of TFP of female students of the elective direction "Volleyball", to compare the level of development before the pandemic (2020) and today's (2022), to assess the consequences of the remote format in the physical development of female students, to suggest ways to take into account monitoring data in educational -training process. The data obtained as a result of testing were qualitatively and quantitatively processed, and presented in this article.

Copper-Sulfur-Nitrogen Cluster Providing a Local Proton for Efficient Carbon Dioxide Photoreduction.

Atomically precise Cu clusters are highly desirable as catalysts for CO2 reduction reaction (CO2 RR), and they provide an appropriate model platform for elaborating their structure-activity relationship. However, an efficient overall photocatalytic CO2 RR with H2 O using assembled Cu-cluster aggregates as single component photocatalyst has not been reported. Herein, we report a stable crystalline Cu-S-N cluster photocatalyst with local protonated N-H groups (denoted as Cu6 -NH). The catalyst exhibits suitable photocatalytic redox potentials, high structural stability, active catalytic species, and a narrow band gap, which account for its outstanding photocatalytic CO2 RR performance under visible light, with ≈100 % selectivity for CO evolution. Remarkably, systematic isostructural Cu-cluster control experiments, in situ infrared spectroscopy, and density functional theory calculations revealed that the protonated pyrimidine N atoms in the Cu6 -NH cluster act as a proton relay station, providing a local proton during the photocatalytic CO2 RR. This efficiently lowers the energy barrier for the formation of the *COOH intermediate, which is the rate-limiting step, efficiently enhancing the photocatalytic performance. This work lays the foundation for the development of atomically precise metal-cluster-based photocatalysts.

Is there a link between carbon isotopes and sea level in epicontinental carbonate settings?

A presumed link between carbon isotopic trends and sea level change features prominently in many studies of epicontinental carbonates. In these shallow marine environments, a combination of basin restriction, burial/oxidation of organic carbon, proximity to terrestrial carbon sources, carbonate mineralogy, and/or meteoric influence can result in δ13Ccarb records that are distinct from that of the open ocean. Because many of these processes are linked to sea level change, it has been argued that sea level might exert a significant and systematic control on the δ13Ccarb records from epicontinental settings. Multiple studies have attempted to document sea level's influence on carbon isotopic trends, but they do so with only limited constraints on sea level change and without objective evaluations of interpreted trends and relationships. We argue that the complex and complicated set of processes influencing carbon isotopic values in epicontinental settings requires a systematic approach to truly address the question of sea level's influence on δ13Ccarb. Only by integrating carbon isotopic records with a detailed sedimentological and sequence stratigraphic framework can we properly track changes in depositional environments and reconstruct the transgressive-regressive history of the rocks. Trends and relationships in these robust datasets can be evaluated with rank correlation tests specifically designed and empirically tested to deal with noisy datasets. In short, we map a possible path forward for systematic testing of the relationship between sea level and δ13Ccarb.

Flying Parker Solar Probe to touch the Sun

For the first time in history, Parker Solar Probe touched the Sun in April 2021 when it entered the Sun's corona—humanity's first mission ever that reached the Sun—for a scientific in-situ study to unlock the mystery of our star. To reach the Sun is extremely difficult because, unlike any other space exploration destination, the Sun is the solar system's central body, around which Earth and other planets revolve. Earth orbits the Sun at a velocity of about 30 km/s, so for a spacecraft to reach the Sun from Earth the spacecraft must cancel out its velocity in the Earth orbit so it can fall to the Sun. That requires an excessively large energy higher than that required to reach any destination in the solar system, which is beyond the capability of current rockets. This paper describes how Parker Solar Probe is delivered to the Sun through a unique V7GA trajectory that enables it to attain the excessive energy through planetary gravity assists of Venus, flying by Venus seven times to ultimately come within 9.86 solar radii (RS) of the Sun. An emphasis is on in-flight trajectory control of the probe through the intricate V7GA trajectory in actual operation in an unprecedented space environment around the Sun, where unpredictable orbit perturbations plus their ripple effects on the consecutive seven Venus flybys could easily drive the flight trajectory out of control. A novel systematic 2-level control method is developed and has been applied to solve the complicated trajectory control problem in flight operation, using in-flight trajectory re-optimization to select the targets of Venus flybys as trajectory control points and then using trajectory correction maneuvers to target a Venus flyby at the control point. This method enables effective and efficient control of the intricate V7GA trajectory and has resulted in significantly better than pre-launch anticipated flight performance, saving tremendous ΔV. Four years from launch, Parker Solar Probe has completed 5 of the 7 Venus gravity-assist flybys and 12 of the 24 planned solar encounters, passing by the Sun at 13 RS in its orbit. Flight results and performance of the completed flight to date are also described.

Improvement of financial and management reporting on land reclamation works at agricultural enterprises

Subject. This article discusses the issues of land reclamation measures that would allow returning idle lands to the cultivated areas, and the organization of their qualitative accounting and control. Objectives. The article aims to develop and improve the forms of financial and management reporting on land reclamation work at agricultural enterprises in the context of digitalization. Methods. For the study, I used a dialectical approach, observation, synthesis, and analysis. Results. The article proposes to apply the forms of reporting that can help build a systematic control of reclamation measures in several areas of analytical accounting at an agricultural enterprise. It also proposes certain clarifications of the sectoral and working Chart of Accounts for agricultural enterprises. Conclusions and Relevance. The study of industry configurations created on the basis of the 1C platform made it possible to conclude that in management subsystems, reporting forms for land reclamation are practically not presented, and in the financial subsystem there are standard trial balance sheets, which do not allow to fully cover all aspects of subject area control. The implementation of the proposed recommendations to improve the methodological support of internal control of the costs of land reclamation work will help form an objective conclusion on the results of the audit and provide the management of the agricultural organization with information for making management decisions. The results of the study can be used in accounting and internal control at agricultural organizations.

Control of stochastic and inverse stochastic resonances in a liquid-crystal electroconvection system using amplitude and phase noises

Stochastic and inverse stochastic resonances are counterintuitive phenomena, where noise plays a pivotal role in the dynamics of various biological and engineering systems. Even though these resonances have been identified in various systems, a transition between them has never been observed before. The present study demonstrates the presence of both resonances in a liquid crystal electroconvection system using combined amplitude and phase noises, which correspond to colored noises with appropriate cutoff frequencies (i.e., finite correlation times). We established the emergence of both resonances and their transition through systematic control of the electroconvection threshold voltage using these two noise sources. Our numerical simulations were experimentally confirmed and revealed how the output performance of the system could be controlled by combining the intensity and cutoff frequency of the two noises. Furthermore, we suggested the crucial contribution of a usually overlooked additional phase noise to the advancements in various noise-related fields.

Surgical safety: effectiveness based on collective intelligence and implementation challenges (review)

The authors used databases Scopus, PubMed, Web of Science, MedLine, RSCI for a systematic periodicals review on surgical safety issues published from 2000 to 2022. The literature review has shown that organization of interaction and communication, quality of completion of the checklist, assessment of the clinical effectiveness of the checklist, possibility of adapting the checklist to the conditions of a particular surgical department, increased compliance of healthcare professionals with the use of the surgical safety checklist, possibility of patient participation in completing the checklist appear to be the basic issues requiring a critical look and a prospective discussion. The introduction of individual components of quality control and medical care safety is known to be a rather long and staged process, during which systematic approaches, starting points and control points are repeatedly reviewed. The high level of specialists training and concentration, the need for clear communications within the surgical team, strict follow the preventive rules can serve as the initial guidelines requiring constant training control. The process principle of quality service management and the incorporation of new technologies for optimization filling and digitalization of the checklist will improve the efficiency and effectiveness of surgical safety.

IoT based smart irrigation, control, and monitoring system for chilli plants using NodeMCU-ESP8266

Traditionally, chilli plant irrigation relies solely on rainwater, which leads to uncontrolled and excessive water consumption and, in turn, unhealthy growth. Furthermore, existing cultivation systems lack systematic control and monitoring to sustain efficient crop growth. Much effort has been put into developing plant irrigation control and monitoring systems in recent decades, resulting in significant technological advancements in the agricultural sector. This paper describes the development of an internet of things-based irrigation control and monitoring system testbed for a chilli plantation. A DHT11 sensor, comprising of moisture, temperature and humidity sensors, were integrated with a node microcontroller NodeMCU ESP8266 unit interacting via wireless fidelity. A controller system that could remotely control the irrigation system was placed in the plantation area. Users interacted with the system through a user interface platform developed using Blynk and Thinger.io. Hence, real-time sensor data were sent to the user interface platform and represented in an easy-to-interpret manner. The results show that the irrigation system testbed can also control the amount of water used, ensuring efficient plant growth.

Development of a Systematic Quality Control Program for Point-of-Care Glucose Testing

Development of a Systematic Quality Control Program for Point-of-Care Glucose Testing

Tuning Surface Reactivity and Electric Field Strength via Intermetallic Alloying.

Many electrosynthesis reactions, such as CO2 reduction to multicarbon products, involve the formation of dipolar and polarizable transition states during the rate-determining step. Systematic and independent control over surface reactivity and electric field strength would accelerate the discovery of highly active electrocatalysts for these reactions by providing a means of reducing the transition state energy through field stabilization. Herein, we demonstrate that intermetallic alloying enables independent and systematic control over d-band energetics and work function through the variation of alloy composition and oxophilic constituent identity, respectively. We identify several intermetallic phases exhibiting properties that should collectively yield higher intrinsic activity for CO reduction compared to conventional Cu-based electrocatalysts. However, we also highlight the propensity of these alloys to segregate in air as a significant roadblock to investigating their electrocatalytic activity.

Nonlinear Dynamic Model-Based Position Control Parameter Optimization Method of Planar Switched Reluctance Motors

Currently, there are few systematic position control parameter optimization methods for planar switched reluctance motors (PSRMs); how to effectively optimize the control parameters of PSRMs is one of the critical issues that needs to be urgently solved. Therefore, a nonlinear dynamic model-based position control parameter optimization method of PSRMs is proposed in this paper. First, to improve the accuracy of the motor dynamics model, a Hammerstein–Wiener model based on the BP neural network input–output nonlinear module is established by combining the linear model and nonlinear model structures so that the nonlinear and linear characteristics of the system are characterized simultaneously. Then, a position control parameter optimization system of PSRMs is developed using the established Hammerstein–Wiener model. In addition, with a self-designed simulated annealing adaptive particle swarm optimization algorithm (SAAPSO), the position control parameter optimization system is performed offline iteratively to obtain the optimal position control parameters. Simulations and experiments are carried out and the corresponding results show that the optimal position control parameters obtained by the proposed method can be directly applied in the actual control system of PSRMs and the control performance is improved effectively using the obtained optimal control parameters.

Effect of material properties on the laser-induced desorption of hydrogen from tungsten

One of the priority tasks for sustainable operations of future fusion devices is the systematic control of hydrogen isotope content in plasma-facing components. A remote non-damaging analysis of the gas content can be realised by applying laser-induced desorption (LID). LID is based on local heating of the studied surface, followed by the detection of desorbed particles. Interpretation of the LID measurements relies on the definition of effective desorption region from which particles are being released. This region strongly depends on the properties of a laser pulse, an analysed material, and defect centres containing hydrogen isotopes. To investigate the role of these properties on LID, a series of numerical simulation was conducted for the case of hydrogen release from a 10 μm tungsten layer, initiated under nanosecond, microsecond, and millisecond heat loads. The simulations were performed using a common reaction-diffusion model with sequentially varied tungsten thermal conductivity, detrapping energy of hydrogen from traps, concentration of hydrogen traps, and their initial filling ratio. Additionally, the Soret effect was considered in order to estimate its impact on the LID efficiency. Findings reveal that the peak surface temperature reached during heating can characterise the LID efficiency under a particular heat pulse. The LID efficiency dependence on the peak surface temperature weakly varies with material thermal properties, but can alter with the change of trap parameters. The detrapping energy of hydrogen from traps considerably influences the desorption efficiency, while concentration and the initial filling ratio of traps have a moderate effect. The Soret effect is shown to noticeably affect the LID efficiency per a laser pulse only at near-melting temperatures of tungsten. Finally, results demonstrate that the highest desorption efficiency from thick layers can be reached using laser pulses with millisecond duration regardless of surface effects, when the release under short-term pulses can be limited by them.

Choice of data visualization tool: FRED or spreadsheets?

We study the impact that the choice of data visualization tool has on student ability to create a graph and interpret the information contained in it. We use a systematic random assignment approach and control for student demographic and academic characteristics. We compare the use of spreadsheets to the use of FRED (Federal Reserve Economic Data) among 471 undergraduate students of statistics for business and economics. We find that although there is no statistical difference between groups in the number of started assignments, the number of completed FRED assignments is significantly larger than the number of completed Google Sheets assignments. With that caveat, we find no association between the choice of data visualization tool and the proportion of correctly built graphs, average frustration, and perceived difficulty reported by students when building the graph. We document lower confidence in the task among female students and students who used FRED.

CONSTRAINT CURRENT CONTROL FOR GRID-CONNECTED POWER INVERTER

Recent study has paid much attention in the areas of renewable energy (solar and wind) as an alternative method to derive electrical power rather than going by fossil fuels (coal, natural gases etc.) which constantly emits carbon dioxide and other harmful substances into the atmosphere. The emission of these undesirable harmful substances into the atmosphere have caused climatic changes for example global warming, acid rain, low precipitations and unwanted desert encroachment. These badly affect the quality life of humans and animals. In response to these problems, methods of reducing carbon content emissions become necessary through the use of renewable energy sources (Photovoltaic system, Wind power, Fuel cell etc.). As a result, research on grid-connected inverter have recently become a very hot topic as a means of interfacing renewable energy sources to utility grid. With good interfacing, the renewable energy sources can be able to solve not only the problem of carbon emissions into the atmosphere but also to efficiently support the grid from increased demand of electrical power. Thus, this research has focused on designing a constraint current controller for grid-connected inverter using linear quadratic regulations (LQR) method. The idea of using LQR control design as opposed to classical PI controller is that The LQR provides optimal current control by careful tuning of the input and state weighting matrices and therefore systematic control design can be achieved. Another advantage of LQR method is that constraint handling can be address through an offline optimization technique. This is necessary in order to protect the inverter system components (semiconductor switches) and improve its reliability.

Improved Indoor Positioning Model Based on UWB/IMU Tight Combination with Double-Loop Cumulative Error Estimation

With the increasing applications of UWB indoor positioning technologies in industrial areas, to further enhance the positioning precision, the UWB/IMU combination method (UICM) has been considered as one of the most effective solutions to reduce non-line-of-sight (NLOS) errors. However, most conversional UICMs suffer from a high probability of positioning failure due to uncontrollable and cumulative errors from inertial measuring units (IMU). Hence, to address this issue, we improved the extended Kalman filter (EKF) algorithm of an indoor positioning model based on UWB/IMU tight combination with a double-loop error self-correction. Compared with conventional UICMs, this improved model consists of new modules for fixing time desynchronization, optimizing the threshold setting for UWB ranging, data fusion in NLOS, and double-loop error estimation, sequentially. Further, systematic error controllability analysis proved that the proposed model could satisfy the controllability of UWB indoor positioning systems. To validate this improved UICM, inevitable obstacles and atmospheric interferences were regarded as Gaussian white noises to verify its environmental adaptability. Finally, the experimental results showed that this proposed model outperformed the state-of-the-art UWB-based positioning models with a maximum deviation of 0.232 m (reduced by 83.93% compared to a pure UWB model and 43.14% compared to the conventional UWB/IMU model) and standard deviation of 0.09981 m (reduced by 88.35% compared to a pure UWB model and 22.21% compared to the conventional UWB-IMU model).

Cooperation in an uncertain environment: The impact of stakeholders' concerted action on collaborative innovation projects risk management

Due to the impact of the epidemic, the risk management strategies of stakeholders in the project have undergone significant changes. Recently, more and more companies have adopted collaborative innovation to develop new businesses. While in an uncertain environment, it is difficult for stakeholders to generate complete trust to integrate resources to achieve systematic management of project risks. Concerted action by stakeholders becomes a viable solution to this problem. Based on collaborative theory and risk management lifecycle, this paper proposes a stakeholder-risk integration analysis framework and builds a double-layer network model to verify it. A case study was conducted, including parallel simulation experiments with different concerted action strategies. The results show that project risks can be effectively controlled when stakeholders take concerted actions to deal with the risks. Under the conditions of complex stakeholder and risk relationships in collaborative innovation projects, stakeholders can achieve systematic risk control through behavioral cooperation without devoting their personal resources, which is beneficial to protect stakeholders' interests. Our research will contribute to the theory by promoting risk management research from the perspective of resource integration to organization and action integration. Finally, we make recommendations for management and future research.

Localized keyhole pore prediction during laser powder bed fusion via multimodal process monitoring and X-ray radiography

Systematic fault detection and control during laser powder bed fusion (L-PBF) has been a long-standing objective for system manufacturers and researchers in the additive manufacturing (AM) industry. This manuscript investigates a data fusion approach for detection of keyhole porosity formation during laser irradiation of Ti-6Al-4V substrates by concurrent recording of thermally induced optical emission measured using both off-axis and coaxial photodiode sensors, and acoustic emission. Subsurface defect formation was monitored via high-speed synchrotron X-ray imaging at 20,000 frames per second, enabling temporal registration of keyhole pore formation events to the monitoring signals at a resolution of 50 µs. We developed data fusion machine learning (ML) models for localized prediction of keyhole pore formation at various time scales ranging from 0.5 ms to 2 ms. The signal segments were featurized using two independent approaches: (1) power spectral density (PSD) and (2) highly comparative time series analysis (HCTSA) framework. The extracted features from different sensor modalities were fused together to construct a multimodal feature space and sequential feature selection was used to determine the most informative features for training the ML models. The predictive performance was evaluated for three classifying algorithms: Support Vector Machine (SVM), K-Nearest Neighbor (KNN), and Gaussian Naive Bayes (GNB). As a result, pore formation events were predicted with up to 0.95 F1-score, 1.0 recall and 0.94 accuracy. The most heavily weighted features indicate that model performance is chiefly governed by the acoustic monitoring signal, with a secondary contribution from the optical emission sensors.

Strong‐field coherent control of the proton momentum distribution arising from the n$$ n $$‐photon (n=1,2,3$$ n=1,2,3 $$) field‐dressed adiabatic potentials of H2+$$ {}_2^{+} $$

AbstractA systematic directionality coherent control of total proton momentum distributions in the dissociative‐ionization of H subjected to a strong field of six‐cycle laser pulses in a full range of carrier‐envelope phase is studied by solving a non‐Born‐Oppenheimer time‐dependent Schrödinger equation numerically. The trend of distributions involves insightful investigation into the spatial‐temporal overlap between nuclear wave packets evolving on the coupled field‐dressed electronic potentials of H associated with the ‐photon potential crossings. This leads to new quantum images for the nonlinear nonperturbative interaction of H with a strong field. It turns out that the symmetry of the ‐dependent momentum distribution begins to break after undergoing interaction with one‐photon field‐dressed potentials. At this point, the most probable proton momentum distribution tends to move in a forward direction indicating also that the three‐photon field‐dressed potentials strongly govern the dissociative‐ionization pathway.

Fine-tuning of p-coumaric acid synthesis to increase (2S)-naringenin production in yeast

(2S)-Naringenin is a key precursor for biosynthesis of various high-value flavonoids and possesses a variety of nutritional and pharmaceutical properties on human health. Systematic optimization approaches have been employed to improve (2S)-naringenin production in different microbial hosts. However, very few studies have focused on the spatiotemporal distribution of (2S)-naringenin and the related pathway intermediate p-coumaric acid, which is an important factor for efficient production. Here, we first optimized the (2S)-naringenin biosynthetic pathway by alleviating the bottleneck downstream of p-coumaric acid and increasing malonyl-CoA supply, which improved (2S)-naringenin production but significant accumulation of p-coumaric acid still existed extracellularly. We thus established a dual dynamic control system through combining a malonyl-CoA biosensor regulator and an RNAi strategy, to autonomously control the synthesis of p-coumaric acid with the supply of malonyl-CoA. Furthermore, screening potential transporters led to identification of Pdr12 for improved (2S)-naringenin production and reduced accumulation of p-coumaric acid. Finally, a titer of 2.05 g/L (2S)-naringenin with negligible accumulation of p-coumaric acid was achieved in a fed batch fermentation. Our work highlights the importance of systematic control of pathway intermediates for efficient microbial production of plant natural products.