Operational Space Research Articles

Trends and hotspots in public food procurement: exploring planetary boundaries and human needs in an integrative literature review

Purpose Using an Integrative Literature Review (ILR), this study aims to investigate the components defining the Safe and Just Operating Space (SJOS) within food systems and assess their applicability in decision-making for public food procurement (PFP). Design/methodology/approach Data concerning SJOS implementation in food systems and the criteria used in PFP were retrieved from the Web of Science and Scopus databases, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) protocol. Findings The analysis of the literature highlights that climate change (n = 31; 17%) and water use (n = 29; 16%) are the primary focus areas regarding Planetary Boundaries (PB), followed the nitrogen cycle, land use, biodiversity loss and the phosphorus cycle. In PFP, key criteria linked to PB encompass climate change (n = 19; 7.2%), water use (n = 17; 6.44%) and chemical pollution (n = 17; 6.44%). The social and ethical dimensions underscore labour (n = 18; 6.82%), water (n = 17; 6.44%), income (n = 16; 6.06%) and energy (n = 16; 6.06%). Research limitations/implications Despite the strengths of this study, certain limitations should be acknowledged. Although the inclusion and exclusion criteria for the reviewed articles were clearly defined, it is possible that relevant literature was unintentionally excluded. Expanding the scope to include grey literature – such as government documents, reports, policy statements and statistical reports – could provide additional insights and broaden the scope of the findings. Moreover, the search was limited to the Web of Science and Scopus databases, which may have resulted in the omission of relevant studies, particularly those published in non-English languages or not indexed journals. Practical implications The identified procurement criteria can help public administrators develop guidelines and tools for food procurement that consider the SJOS. Social implications This paper offers an understanding of the connection between planetary processes and human well-being in the context of PFP. Originality/value This pioneering research lays the groundwork for future agendas in this field and encourages reflection on critical factors essential for selecting methods and standards applied in practical public procurement.

Urbanisation from the margins: auto-construction of urban spaces for paratransit services in Kumasi, Ghana

ABSTRACT In Ghana, paratransit services (three-wheeler taxis) have gained prominence because of their role in solving urban mobility challenges in major cities. While they are good at solving urban mobility challenges, they cause accidents and create congestion and inconveniences in the central business districts of cities. However, the literature on how paratransit service operators organise and create spaces for their operations is limited. We draw on peripheral urbanisation theory to understand how the operators produce urban spaces to conduct business in Kumasi. We hope to provide information for the planning and design of infrastructure that meets the needs of the different modes of urban mobility. In doing so, we adopt interviews and focus group discussions involving 35 purposively selected operators, 16 union executives, and two officials from the Kumasi Metropolitan Assembly to elicit the data. The responses were coded and categorised into themes for presentation. Findings indicate that the operators create space through negotiation and site selection. We conclude that securing spaces to conduct business is a major challenge to operators. Therefore, Kumasi Metropolitan Assembly should partner with communities, investors, and operators to create spaces for paratransit operators as it can provide a major source of revenue for development projects.

Decision-making for childhood vaccination in crisis settings: a survey of practice & barriers

Abstract Background Children, particularly those who have received no routine vaccinations (zero-dose children), are at high risk of vaccine-preventable diseases in humanitarian crisis settings. However, the decision-making processes underlying vaccine intervention design and delivery in such settings are poorly understood. The present study investigated the decision-making practices of organisations involved in childhood vaccination in humanitarian crisis settings globally via an online survey. Methods Individuals involved in the design or delivery of childhood vaccination programmes in humanitarian crisis settings were invited to fill out a self-administered online survey. Respondents were asked about factors influencing intervention design and vaccine delivery; use of technical guidance, specifically the WHO decision-making framework for vaccination in acute humanitarian emergencies (WHO Framework); and practices for reaching zero-dose children. Results Fourteen responses were received. Large international organisations and UN agencies were overrepresented in the sample. Technical guidance was considered of high importance when designing vaccine interventions. However, the WHO Framework is not available in relevant languages and has not been well-distributed to local and national actors. Awareness of initiatives to reach zero-dose children was high within our sample, though this may not accurately reflect global awareness. Security and resource availability were key barriers to vaccine delivery and reaching zero-dose children. Problems with vaccine access in our sample pertained primarily to issues with the procurement system rather than vaccine cost. Conclusions The WHO Framework should be provided in more languages, and vaccination actors at local and national level should be engaged to improve its practicality and increase awareness of its aims. In order to reach zero-dose children, vaccines must be made available for use in expanded age groups, which is sometimes not currently feasible within the Gavi/UNICEF procurement system. Clarifying this policy would allow relevant organisations to reach more zero-dose children. Additionally, security is a key barrier impeding vaccine delivery, including for zero-dose children. Safe operational space for humanitarian actors in conflict must be maintained and global conflict resolution mechanisms improved.

Path planning for flexible needle based on both insertion mechanism kinematics and needle bending model.

Due to the limited operating space in the magnetic resonance (MR) environment, there is coupled motion in the insertion mechanism, which not only reduces the flexibility of the robot but also challenges the insertion path planning. Meanwhile, the path planning is also restricted by the bending rule of the flexible needle, thus the bending model of the needle is also essentially built. This paper proposes a path planner for the flexible needle based on both the coupled motion kinematics of the insertion robot and the bending model of the flexible needle. A kinematic analysis for the coupled motion of insertion robot is performed. And the bending model of flexible needle is established based on the needle-tissue interactions. The position and posture of the needle insertion at the entry point are obtained by the calculation of the target position and the analysis of the bending model. And the rotation or translation coordinates of each robot joint are calculated by the inverse kinematics of the insertion robot. Then the path planning based on the coupled kinematics and the bending model is realized. The insertion experiments were performed for each target of G1 and G2. The root mean square errors were 0.83 mm and 0.74 mm, and the maximum errors were 1.1 mm and 0.9 mm for G1 and G2, respectively. The experimental results show that the effectiveness and accuracy of the path planning can meet the requirements for a general minimally invasive surgery, so the proposed path planning algorithm is feasible. This study provides a new solution for the path planning of insertion robots for the minimally invasive surgery. This method can meet the insertion mechanism working within the limited operating space in the MR environment and has a high application value in future clinical medicine.

Post-war restoration of agricultural land: legal perspectives, land disputes and state support

The restoration of agricultural land is a dynamic and complex phenomenon, built on the close interaction of chemical, physical and biological processes, which are accelerated and directed with the help of purposeful organizational and legal measures. Since the land has been used as a space for military operations for almost three years now, it suffers from a number of negative factors that have a powerful synergistic effect: the soil is polluted by various substances; lands are littered with explosive objects and other war debris; the landscape changes due to the construction of fortifications, digging trenches, as a result of strikes, shelling, etc. The post-war restoration of such agricultural lands has its own significant features related to the man-made origin of the violations, the potential danger of the detected pollution and the high cost of restoration works. At the same time, the relevant restoration measures lie in the plane of not only the private interests of specific landowners and land users - they are the sphere of well-defined public interests. The legal issue of the post-war restoration of agricultural lands is considered in three interrelated aspects: 1) in the theoretical aspect - the signs of the independence of demining as a separate type of the main measures of land restoration are determined and it is proposed to reflect this feature in the legislation, in order to emphasize and strengthen the integration of land, agrarian, and environmental legislation and legislation on mine action; 2) in a practical aspect, the potential grounds for the emergence of disputes in the field of post-war land restoration are outlined and the connection between the degree of dispositiveness of the legislative provision and the probability of a compromise solution of such disputes in the mediation procedure is established; 3) in the protective aspect - modern mechanisms of state support for the restoration of lands most affected by hostilities (provision of tax benefits, subsidies, partial compensation for demining costs) were identified and characterized. It was concluded that there is a need to develop a systemic special legislative support for relations with the post-war restoration of agricultural land, taking into account the specified aspects of this multi-level problem.

Application status and considerations of unilateral biportal endoscopy technique

To review the application status, clinical advantages, and complications of unilateral biportal endoscopy (UBE) technique and explore its future development direction. By reviewing recent domestic and international literature, the evolution history of UBE technique, its surgical advantages, and its application effectiveness in various spinal diseases were analyzed, providing a comprehensive review. UBE technique, with its unique dual-channel design, provides a clearer surgical field and more flexible operating space, significantly reduces surgical trauma and postoperative recovery time. UBE technique has demonstrated high safety and effectiveness in the treatment of lumbar disc herniation, spinal stenosis, lumbar instability, and cervical spondylosis. Additionally, the complication incidence of UBE surgery is lower than that of traditional open surgery. In recent years, UBE technique has shown good clinical application prospects and efficacy, but further technical optimization and large-scale clinical research are still needed to ensure the safety and effectiveness. In the future, the combination of UBE technique and intelligent medical and surgical robotics technology is expected to promote the further development of spinal surgery.

Mring: Contactless MR/AR Extended Input Method Based on Magnetic Signal

In recent years, the rapid rise of Mixed Reality (MR) and Augmented Reality (AR) technologies has transformed digital interactions and immersive experiences, as evidenced by their widespread adoption in AR glasses, MR headsets, and mobile AR applications. However, integrating MR and AR into everyday life also presents unique problems, particularly concerning user interactions within limited visual fields and discomfort caused by prolonged arm elevation. To address these challenges, our research introduces an innovative input device utilizing common wearable device magnetometer sensors and a strong magnet as input controls. We employ innovative methods to eliminate environmental magnetic field and soft magnetic offset, achieving trajectory restoration with an error margin of 5.23 mm through machine learning and trajectory smoothing algorithms. This enables our input device to interact with MR and AR devices beyond the user’s visual range, expanding operational space, and enhancing usability.

Explanation of the principles of the Booth algorithm, Verilog implementation and simulation

In an era marked by heightened constraints on computer processing speed and storage capacity, optimizing computational efficiency and space utilization assumes paramount importance. Consequently, the deployment of proficient algorithmic tools holds significant significance within the realm of computing. The principal categories of multipliers encompass conventional multipliers, shift-and-add multipliers, Look-Up Table (LUT) multipliers, and Booth algorithm multipliers. Among these, the Booth algorithm substantially influences multiplier performance enhancement. This paper investigation commences with a comprehensive elucidation of the mathematical underpinnings of the Booth algorithm. Subsequently, it involves the development of code corresponding to the mathematical expressions, which is executed within the VIVADO environment. Given the inherent simplicity of the experiment, virtual simulation is directly conducted in VIVADO. The analysis is grounded in the examination of data waveforms. Ultimately, the output waveform is correlated with the BOOTH mathematical formula, culminating in the successful implementation of the BOOTH algorithm. This paper aims to effectively curtail the presence of '1's in computer data, thereby reducing the computational steps and conserving operational space. This, in turn, leads to a notable acceleration in the computational speed, accomplishing the objective of enhancing computational efficiency.

Diagnostic value of nasal sinus computed tomography/magnetic resonance imaging examination and serum cytokines in unilateral benign sphenoid sinus lesions

ObjectivesDue to the unique anatomical location of the sphenoid sinus and the extremely limited operational space during endoscopic nasal surgeries, even minor procedural errors can lead to severe complications. Hence, comprehensive preoperative assessment is crucial. It was to retrospectively analyze the diagnostic value of nasal sinus computed tomography (CT), magnetic resonance imaging (MRI), and serum interleukin (IL) cytokine levels for unilateral benign sphenoid sinus lesions (UBSSLs). Materials and methodsClinical data from 85 suspected UBSSL patients were collected. Surgical pathology served as the gold standard for evaluation, assessing the diagnostic value of nasal sinus CT, MRI, and serum IL-4, IL-9, and IL-17 levels. ResultsSurgical pathology confirmed 53 cases of UBSSLs. Relative to non-UBSSL patients, those with unilateral benign lesions showed greatly elevated serum levels of IL-4, IL-9, and IL-17 (P < 0.05). The detection rate of UBSSL using the combined CT + MRI approach was significantly higher than that of CT or MRI alone. Similarly, the combined detection rate of IL-4, IL-9, and IL-17 was significantly higher than that of IL-4, IL-9, or IL-17 individually. The detection rate of CT + MRI (88.68%) was higher than that of the IL-4+IL-9+IL-17 combination (75.47%) (P < 0.05). The areas under the receiver operating characteristic curves for diagnosing UBSSL using serum IL combinations, sinus CT + MRI, and IL combinations + CT + MRI were 0.812, 0.840, and 0.905, respectively. Moreover, the accuracy and sensitivity of the IL combinations + CT + MRI approach were higher than those of either the serum IL combinations or sinus CT + MRI alone. ConclusionElevated IL-4, IL-9, and IL-17 were associated with UBSSLs, and their combination with nasal sinus CT/MRI can enhance the diagnostic accuracy of this condition.

Considering Transformative Leadership from a Christian Vantage Point

Theological writing in an advocatory modality seeks to advance a given position through reasoned argumentation designed to persuade a reader of its veracity. This paper exploits a conceptual analysis technique to interrogate the notion of transformative leadership from a Christian perspective considering three key denominations, namely Orthodoxy and Pentecostalism. A literature review methodology was used and we applied an interpretivistic paradigm to arrive at conclusions relating to the important notion of Christian transformative leadership. Using Christian teachings as a hermeneutic key we argue that they have a vital role to play in contributing to the responses made by Churches of all denominations relating to issues of transformational leadership and challenges posed in modern society. The Christian churches irrespective of denomination, are facing mega challenges requiring critical thinking based on Holy Scripture to employ in their operational spaces and also in their activities, and policy formulation relating to the issue of especially leadership. Inventive approaches are required for leaders in organisations to be truly transformational in their approaches. Transformative Church leaders need to be able to guide their congregations to feel free to explore new ideas and prospects that can promote a truly Christian ethos. They should also seek to engender an ethos of value in the Church in which there is a strong sense of purpose in what believers undertake. This paper contends that a transformational Church leader needs to be a true servant of God first and then the Ecclesia. The Transformative Church leader requires a firm mentorship style to assist believers to arrive at the point where they can make a valuable contribution to the House of the Lord and to society at large. Christian Transformational Leadership is today, as was the case millennia ago, one of the main leadership theories through which a Christian leader, strives to transform and influence their followers by expounding on their expected Christian vision and character.

Leveraging RTLS to assess clinical space utilisation

Investment in physical space is a key strategic decision for healthcare managers. Understanding the current utilisation of clinical space is a significant input for this decision. Historically, direct observation or analysis of electronic health record (EHR) timestamps has been used to assess ambulatory space utilisation. Manual observation is prohibitively expensive, prospective and infeasible for large spaces. EHR data is limited to electronically captured workflows and to the quality of data capture. Two pilots explored the efficacy of real-time location systems (RTLS) to assess outpatient space utilisation to assist healthcare management professionals to make space allocation decisions. RTLS was shown to be viable, with accuracy that was not different from EHR-derived utilisation. RTLS had the following benefits: (a) more granular information, (b) data coverage in areas without EHR timestamps and (c) real-time assessment of utilisation. RTLS is an option for ambulatory care managers to understand the needed space for clinical operations.

Resilience of the Atlantic meridional overturning circulation.

We address the issue of resilience of the Atlantic Meridional Overturning Circulation (AMOC) given the many indications that this dynamical system is in a multi-stable regime. A novel approach to resilience based on rare event techniques is presented, which leads to a measure capturing "resistance to change" and "ability to return" aspects in a probabilistic way. The application of this measure to a conceptual model demonstrates its suitability for assessing AMOC resilience but also shows its potential use in many other non-autonomous dynamical systems. This framework is then extended to compute the probability that the AMOC undergoes a transition conditioned on an external forcing. Such conditional probability can be estimated by exploiting the information available when computing the resilience of this system. This allows us to provide a probabilistic view on safe operating spaces by defining a conditional safe operating space as a subset of the parameter space of the (possibly transient) imposed forcing.

Extended Operational Space Kinematics, Dynamics, and Control of Redundant Serial Robots

A recently developed differential geometric representation of redundant serial robot kinematics is employed to create a new extended operational space dynamics and control formulation that explicitly accounts for redundant robot degrees of freedom. This formulation corrects deficiencies in kinematics and dynamics of redundant serial robots that have relied for over half a century on error-prone generalized inverse velocity-based kinematics for redundancy resolution. New ordinary differential equations of robot operational space dynamics are obtained, without the need for ad hoc derivation, in terms of task coordinates and self-motion coordinates that represent robot redundancy. A new extended operational space control approach is presented that exploits ordinary differential equations of motion in terms of task and self-motion coordinates, enabling enforcement of desired output trajectories, obstacle avoidance, and performance constraints. Four examples are presented with a one-degree-of-redundancy robot that demonstrate the validity and superior performance of the new formulation, relative to the traditional task space method used for redundant serial robot control. Finally, an example with eight degrees of redundancy is presented that further illustrates superior performance of the new operational space formulation.

An overview of the STEP divertor design and the simple models driving the plasma exhaust scenario

Abstract This paper presents a comprehensive overview of the preliminary divertor design and plasma exhaust scenario for the reactor-class Spherical Tokamak for Energy Production (STEP) project. Due to the smaller size of the machine, with a major radius less than half that of most DEMO concepts, the current design features a double-null divertor geometry, comprising tightly baffled extended outer legs and shorter inner legs approaching an X-divertor. Leveraging a significant database of SOLPS-ITER simulations, the exhaust operational space is mapped out, offering valuable insights into the plasma exhaust dynamics. An approach involving the validation of simple, yet robust models capable of accurately predicting key exhaust parameters is detailed, thereby streamlining the design process. The simple models are used to simulate the entire plasma scenario from the plasma current ramp-up, through the burning phase, to the plasma current ramp-down. Notably, the findings suggest that pronounced detachment, with peak heat loads below engineering limits and electron temperatures below 5 eV, is achievable with a divertor neutral pressure between 10 - 15 Pa during&amp;#xD;the burning phase, and pressures below 5 Pa during the ramp-up to maximise the auxiliary current-drive efficiency. Throughout the scenario, an Ar concentration of ~3% in the scrape-off layer (SOL) is required, in combination with a core radiation fraction of 70% driven by intrinsic emission and extrinsic injection of Xe seeded fuelling pellets. However, significant uncertainties remain regarding key parameters such as the SOL heat flux width, Ar screening, and plasma kinetic effects.

Miniaturized silicon-based capacitive six-axis force/torque sensor with large range, high sensitivity, and low crosstalk

Miniaturized six-axis force/torque sensors have potential applications in robotic tactile sensing, minimally invasive surgery, and other narrow operating spaces, where currently available commercial sensors cannot meet the requirements because of their large size. In this study, a silicon-based capacitive six-axis force/torque sensing chip with a small size of 9.3 × 9.3 × 0.98 mm was designed, fabricated, and tested. A sandwich decoupling structure with a symmetrical layered arrangement of S-shaped beams, comb capacitors, and parallel capacitors was employed. A decoupling theory considering eccentricity and nonlinear effects was derived to realize low axial crosstalk. The proposed S-shaped beams achieved a large measurement range through stress optimization. The results of a coupled multiphysics field finite-element simulation agreed well with those of theoretical analyses. The test results show that the proposed sensing chip can detect six-axis force/torque separately, with all crosstalk errors less than 2.59%FS. Its force and torque measurement ranges can reach as much as 2.5 N and 12.5 N·mm, respectively. The sensing chip also has high sensitivities of 0.52 pF/N and 0.27 pF/(N·mm) for force and torque detection, respectively.

Deep learning for predicting rate-induced tipping

AbstractNonlinear dynamical systems exposed to changing forcing values can exhibit catastrophic transitions between distinct states. The phenomenon of critical slowing down can help anticipate such transitions if caused by a bifurcation and if the change in forcing is slow compared with the system’s internal timescale. However, in many real-world situations, these assumptions are not met and transitions can be triggered because the forcing exceeds a critical rate. For instance, the rapid pace of anthropogenic climate change compared with the internal timescales of key Earth system components, like polar ice sheets or the Atlantic Meridional Overturning Circulation, poses significant risk of rate-induced tipping. Moreover, random perturbations may cause some trajectories to cross an unstable boundary whereas others do not—even under the same forcing. Critical-slowing-down-based indicators generally cannot distinguish these cases of noise-induced tipping from no tipping. This severely limits our ability to assess the tipping risks and to predict individual trajectories. To address this, we make the first attempt to develop a deep learning framework predicting the transition probabilities of dynamical systems ahead of rate-induced transitions. Our method issues early warnings, as demonstrated on three prototypical systems for rate-induced tipping subjected to time-varying equilibrium drift and noise perturbations. Exploiting explainable artificial intelligence methods, our framework captures the fingerprints for the early detection of rate-induced tipping, even with long lead times. Our findings demonstrate the predictability of rate-induced and noise-induced tipping, advancing our ability to determine safe operating spaces for a broader class of dynamical systems than possible so far.

Deep Reinforcement Learning-Assisted Teaching Strategy for Industrial Robot Manipulator

This paper introduces an innovative algorithm aimed at enhancing robot learning using dynamic trajectory modeling and time-dependent state analysis. By integrating reinforcement learning (RL) and trajectory planning, the proposed approach enhances the robot’s adaptability in diverse environments and tasks. The framework begins with a comprehensive analysis of the robot’s operational space, focusing on Cartesian coordinates and configuration systems. By modeling trajectories and states within these systems, the robot achieves sequential tracking of arbitrary states, facilitating efficient task execution in various scenarios. Experimental results demonstrate the algorithm’s efficacy in manipulation tasks and path planning in dynamic environments. By integrating dynamic trajectory modeling and time-dependent state analysis, the robot’s adaptability and performance improve significantly, enabling precise task execution in complex environments. This research contributes to advancing robot learning methodologies, particularly in human–robot interaction scenarios, promising applications in manufacturing, healthcare, and logistics.

Load Cycling Durability Protocols for Predictive MEA Lifetime Modeling for Long-Life PEMFC Applications

As the large-scale commercialization of proton exchange membrane fuel cells (PEMFC) for numerous heavy-duty applications draws nearer, there is an increasing emphasis on the delivery of highly robust membrane electrode assemblies (MEAs) capable of achieving upwards of 25,000 hours of on-road durability (1). A particular area of MEA durability focus is that of the proton conducting perfluorosulfonic acid (PFSA) membrane which is subjected to varying degrees of oxidative stress during fuel cell operation. The development of highly durable membranes necessitates the implementation of accelerated testing protocols that can be used to determine the sensitivity of membrane lifetime to a number of operational parameters such as cell temperature and membrane humidification. The objective of sensitivity studies is to develop robust and predictive degradation models using state-of-the-art (SOA) MEAs under the accelerated operational space that can be subsequently applied to the milder operational space of a long-lifetime application. Traditionally, open circuit voltage (OCV) degradation studies have been employed to assess membrane durability. While OCV degradation experiments can be highly accelerating from a chemical degradation perspective, producing high fluoride release and membrane thinning rates, the operating conditions do not sufficiently emulate the dynamic chemical stresses generated under load nor do they provide RH cycling and concomitant mechanical stresses that accompanies load cycling (2). At the other end of the cell load continuum, constant current durability tests have consistently failed to produce high degradation rates, even in the presence of Fe accelerants.In response to the recognized shortcomings of OCV and related accelerated durability tests, we have developed a suite of flexible, single-cell, load-cycling durability tests that more closely emulate stresses experienced in variety of real-world, on-load applications. Test protocols enable the variation numerous operational parameters including temperature, inlet RH, high and low cycling current densities and the ratio of time spent at the high and low current densities. In-situ degradation rates are assessed by monitoring emitted fluoride concentrations at regular intervals. Cerium-mitigated (3), SOA PFSA membranes fabricated with PtCo/HSC cathode electrodes are quite robust even under the harshest load cycling conditions (110 °C/ 30% RH), producing fluoride release rate (FRR) values less than 1x10-8 gF/cm-2h-1. The creation of predictive chemical degradation models requires significant and quantifiable chemical degradation signals to occur across accelerated the reaction space continuum. Therefore, given the high stability of SOA membranes, the degradation rates are further accelerated by the addition of Fe2+ Fenton’s catalysts. The Figure below shows the FRR profiles obtained from a series of four MEAs, differing only in the amount of added Fe2+ prior to the durability test conducted at 95 °C/30% RH with load cycling between 0.02-1.5 A/cm². In addition to Fe sensitivity findings, we will present data regarding sensitivities of degradation rates with respect to temperature, inlet RH, high current density values and time ratios at high and low current densities.(1) D. A. Cullen, K. C. Neyerlin, R. K. Ahluwalia, R. Mukundan, K. L. More, R. L. Borup, A. Z. Weber, D. J. Myers, A. Kusoglu, Nature Energy, 6, 462–474 (2021)(2) C. S. Gittleman, F. D. Coms, Y.-H. Lai, In Polymer Electrolyte Fuel Cell Degradation, M. Matthew, K. E. Caglan, T. N. Veziroglu, Editors, p. 15, Academic Press, Boston (2012)(3) F. D. Coms, H. Liu, and J. E. Owejan, ECS Transactions, 16, 1735 (2008) Figure 1

Flexible operation space of hydro–hydrogen–based hybrid power systems

Schedulable hydropower and hydrogen power provide essential flexibility to mitigate variability of renewables such as wind and photovoltaic power. Previous research has focused on the flexibility of power systems utilizing a single adjustable source (e.g., hydropower). However, joint flexibility of combining adjustable hydropower and hydrogen power has rarely been explored simultaneously. This study aims to establish a joint flexible operation framework for hydro–hydrogen–wind–photovoltaic hybrid power systems. Initially, the forecast uncertainties are quantified regarding the inflow as well as the combined wind and photovoltaic power. Subsequently, a tri-objective optimization model is formulated to maximize operation benefits while enhancing joint flexibility in managing water levels and allocating power to hydrogen production, deriving the flexible operation space. Finally, the operation space's effectiveness is validated by stochastic simulation. Results from a case study using China's Ertan hydro–hydrogen–wind–photovoltaic hybrid power system indicated that the minimum operation benefit derived from the decisions within the operation space decreased with increasing flexibilities of both the water level and power allocation to hydrogen production. The benefit loss (i.e., the gap between the theoretical maximum and actual benefits) decreased by 26.53 %, from 3.77 to 2.77 million CNY, through maintaining operation decisions within the flexible space during a hypothetical earthquake emergency. This was achieved by adjusting 1.79 % release and 10.71 % hydrogen production power. The proposed method provides implications of jointly utilizing flexibilities of adjustable power sources to decrease economic loss. This research contributes to reducing energy emissions by improving energy use efficiency of power systems.

Earth: An Oxidative Planet with Limited Atom Resources and Rich Chemistry.

Humanity faces an unprecedented survival challenge: climate change, driven by the depletion of natural resources, excessive waste generation, and deforestation. Six out of nine planetary boundaries have been exceeded, signaling that Earth is far from a safe operating space for humanity. In this Viewpoint Article we explore three critical "atomic-molecular" challenges: Earth's limited atomic resources, its oxidative nature, and very rich chemistry. Addressing these requires a transformation in how we produce and consume, emphasizing sustainable practices aligned with the United Nations' 17 goals. The advancement of science and technology has extended human life expectancy and improved quality of life. However, to ensure a sustainable future, we must move towards less oxidative chemical processes, incorporate CH4-CO2 redox chemistry into the circular economy, and transition from a linear, fossil fuel-dependent economy to a circular bioeconomy. Reforestation and the recovery of degraded lands are essential, alongside the shift towards green and sustainable chemistry. Earth's dynamic chemistry is governed by the principles of thermodynamics and kinetics, but science alone is insufficient. Achieving global sustainability requires coordinated economic, political, and social decisions that recognize Earth's limited resources and oxidative nature. Together, these efforts will position humanity to meet the challenges of climate change and secure a sustainable future.