Mechanical Power Research Articles

The contractile efficiency of the mantle muscle of European common cuttlefish (Sepia officinalis) during cyclical contractions.

Escape jet propulsion swimming in cuttlefish (Sepia officinalis) is powered by the circular muscles surrounding the mantle cavity. This mode of locomotion is energetically costly compared with undulatory swimming. The energetic cost of swimming is determined by the mechanical power requirements and the efficiency with which chemical energy is transferred into useful mechanical work. One step in this energy transduction process is the transfer of energy from ATP hydrolysis into mechanical work by the muscles. Here, we determined the efficiency of this step, termed the contractile efficiency. Muscle preparations from the circular muscles of the mantle cavity were subjected to sinusoidal length changes at different cycle frequencies, and stimulated with a phase and duration that maximised initial net work. Changes in ATP, arginine phosphate and octopine content between control and exercised muscles were determined and used to calculate the energy released from ATP hydrolysis (Emet). The maximum contractile efficiency (the ratio of net work to Emet) was 0.37, occurring at the same cycle frequency at which mechanical power was maximal and that was used during jet propulsion swimming, suggesting that cuttlefish muscle is adapted to generate muscular power efficiently. The overall efficiency of cuttlefish jet propulsion swimming was estimated to be 0.17, which is broadly comparable to that measured during animal flight and human-powered pedalled locomotion, indicating the high energetic costs of jet propulsion swimming are not due to inefficient locomotion per se; instead, they result from the relatively high mechanical power requirements.

Robust Adaptive type 1 Fuzzy Logic Control for permanent magnet synchronous motor

In this paper we will present a new adaptive control technique based on type 1 fuzzy controllers to control the mechanical power generated by a permanent magnet synchronous motor, this machine is powered by two converters in series. One converter on the network side to control the direct current bus and improve the power factor on the network side, the other on the motor side to regulate the mechanical power (speed, torque) produced by our motor. We will then present a comparative study between the developed controller and other conventional controllers to highlight the best performing and most robust of each, this comparative study is based on a series of tests that we have carried out during the transient and continuous operation of our permanent magnet synchronous motor under the same conditions. The numerical simulations demonstrate the effectiveness of the implementation of the typical adaptive type 1 fuzzy control to achieve these objectives.

An innovative approach to direct recovery and storage of natural gas depressurization wasted energy by using a hybrid pumped-hydro and compressed gas system

A novel mechanism is proposed to simultaneous recovery and storage of energy for use in the natural gas depressurization process. The main idea of this proposal is to use a compressor and a pump coupled with the turbo-expander to directly store the mechanical power produced by the expansion turbine in the energy storage system based on the pumped hydro combined with compressed gas. The compressor is used to create preset pressure in the vessel of the energy storage system, and the pump is used to inject water into the vessel. In this way, the density of energy storage in the system increases. In the discharge stage, electricity is produced by passing water through the turbo-generator during peak consumption hours or when energy prices are higher. The capability of the presented new method has been tested in a natural gas pressure reducing station with a nominal capacity of 50,000 Nm3/h, and the effect of different factors within the energy storage system on its performance, including the preset pressure and the volumetric ratio of water to gas in the pressurized tank, has been studied. By using the proposed plan, due to the elimination of unnecessary energy conversions the efficiency of recovery, storage and release of energy enhances. The results showed that by employing the proposed system, about 1.3 (GWh) of energy can be harvested annually; while this amount of energy is currently wasted. Also, the overall energy conversion efficiency of 48.64 %.

Charge storage mechanism and pseudocapacitance performance of NiO and Ce-doped NiO synthesized via modified combustion technique

Supercapacitors, as promising energy storage devices, have gained significant attention due to their ability to deliver high power and efficient charge storage mechanisms. In this work, we report the synthesis and electrochemical characterization of pristine NiO and Ni1-xCexO (x = 0.01, 0.02, 0.03) nanoparticles using a single-step auto ignition combustion method. Preliminary investigations indicate that Ni1-xCexO (x = 0.02) nanoparticles (2 % Ce doping) exhibit superior specific capacitance compared to other compositions. Therefore, we focused on structural, morphological, and vibrational studies on pristine and 2 % Ce-doped NiO. XPS and BET techniques were explored to assess the electronic state and porosity of the samples. Subsequent electrochemical performance evaluations included Cyclic Voltammetry (CV) at various scan rates, Galvanostatic Charge-Discharge (GCD), and Electrochemical Impedance Spectroscopic (EIS) techniques. From CV at a scan rate of 5 mVs−1, specific capacitance values of 419 Fg-1 and 604 Fg-1 were obtained for pristine and 2 % Ce-doped NiO, respectively. GCD studies revealed a specific capacitance of 381 Fg-1 for 2 % Ce-doped NiO at a current density of 1 Ag-1 and demonstrated capacitance retention of 95.1 % over 3000 GCD cycles for a current density of 4 Ag-1. The symmetric two-electrode supercapacitor cell demonstrates exceptional electrochemical performance, exhibiting a high specific capacitance of 122 Fg-1, an impressive energy density of 8.17 WhKg−1, a power density of 700 WKg-1 at 1 Ag-1, and a remarkable 88 % capacitance retention after 5000 GCD cycles. DFT calculations suggest that Ce doping significantly alters pristine NiO's electronic and structural features due to lattice strain. Our work highlights the enhanced electrochemical performance of 2 % Ce-doped NiO and its potential as a good-quality supercapacitor material.

Assessing the impacts of public policies towards environmental sustainability in the Centre NUTII of Portugal. The case of POSEUR (2014-2020)

The operational programme for Sustainability and Use of Resources (POSEUR 2014-2020) is the most powerful mechanism of EU Cohesion Policy to be implemented in Portugal concerning sustainable environmental development. The programme has a place-based approach that attends to the territorial characteristics of the Portuguese regions. This study focused its analysis on the POSEURS’ main impacts on the Portuguese Centre NUT II. With a mixed methodological approach, impact scores were produced for five environmental sustainability dimensions: i) low-emissions economy, ii) adaptation to climate change, iii) risk prevention and management, iv) environmental protection, and v) resource efficiency. The qualitative and quantitative data was collected through interviews, literature review, the POSEUR project database analysis and regional environmental indicators. The outcome of the analysis showed that technical and execution barriers contributed to the heterogeneity of the results obtained in the five selected dimensions. An overall balance points out the low positive impact scores promoting small regional changes in environmental sustainability. Nonetheless, elaborating spatial plans for the municipalities and regions turned the adaptation to climate change into a highly positive impact dimension.

Decrees of the President of the Russian Federation as a source of financial law

The problem of subordinate rule-making is one of the most pressing in the theory and practice of financial law. This is explained by a number of reasons, one of which remains the need to build an internally consistent system of financial and legal regulation. Decrees of the President of the Russian Federation occupy a special place in this system due to its special position in the mechanism of state power. At the same time, the legal nature of the decrees has not been sufficiently studied and requires additional research. The subject of the study is the legal nature and role of Decrees of the President of the Russian Federation in the context of increasing restrictive measures (sanctions) on the part of unfriendly countries. The regulation of financial and legal relations through Decrees of the President of the Russian Federation is analyzed, reflecting the problems of theory and practice.

그림책으로 읽어보는 어린이의 몸과 건강: 푸코의 지식, 권력과 담론을 기초로

Objectives This study aimed to analyze how picture books discuss and represent children's bodies and health, as well as to uncover their underlying meanings, utilizing the concepts of knowledge, power, and discourse by the post-structuralist M. Foucault. Methods To achieve this, a discourse analysis was conducted using Foucault's techniques of discipline, surveillance, and normalization on 132 picture books selected through the search of the National Library for Children and Young Adults. Results The findings revealed that these picture books reflect the standards and norms set by our society regarding children's bodies and health. They utilize the authority and status of specialized knowledge in fields such as medicine, nutrition, psychology, and sports science to regulate children's bodies by presenting different arrangements of healthy or vulnerable bodies and establishing hierarchical knowledge to secure a standardized body position. The multiplicity of voices, including the voice of narrators, illustrations, and the voice of adult readers, intertwined with gazes between characters, exerted the power of reward and punishment, allowing child readers to self-regulate regarding their bodies and health. Moreover, the ideal characteristics of children's bodies and health were reinforced through powerful discourses structured around expectations, commands, conventions, norms, declarations, and linked to broader societal discourses such as risk and deficiency, differentiated by age and gender. Conclusions The meaning and discourse surrounding children's healthy bodies were discussed within the context of how societal discourses, including risk and deficiency discourses based on age and gender, also regulate children's bodies and health. Picture books by adopting a narrative form can become a mechanism of power that (re)produces and disseminates knowledge and discourse about children.

Biomechanical and morphological determinants of maximal jumping performance in callitrichine monkeys.

Jumping is a crucial behavior in fitness-critical activities including locomotion, resource acquisition, courtship displays and predator avoidance. In primates, paleontological evidence suggests selection for enhanced jumping ability during their early evolution. However, our interpretation of the fossil record remains limited, as no studies have explicitly linked levels of jumping performance with interspecific skeletal variation. We used force platform analyses to generate biomechanical data on maximal jumping performance in three genera of callitrichine monkeys falling along a continuum of jumping propensity: Callimico (relatively high propensity jumper), Saguinus (intermediate jumping propensity) and Callithrix (relatively low propensity jumper). Individuals performed vertical jumps to perches of increasing height within a custom-built tower. We coupled performance data with high-resolution micro-CT data quantifying bony features thought to reflect jumping ability. Levels of maximal performance between species - e.g. maximal take-off velocity of the center of mass (CoM) - parallel established gradients of jumping propensity. Both biomechanical analysis of jumping performance determinants (e.g. CoM displacement, maximal force production and peak mechanical power during push-off) and multivariate analyses of bony hindlimb morphology highlight different mechanical strategies among taxa. For instance, Callimico, which has relatively long hindlimbs, followed a strategy of fully extending of the limbs to maximize CoM displacement - rather than force production - during push-off. In contrast, relatively shorter-limbed Callithrix depended mostly on relatively high push-off forces. Overall, these results suggest that leaping performance is at least partially associated with correlated anatomical and behavioral adaptations, suggesting the possibility of improving inferences about performance in the fossil record.

The impact of PEEP on mechanical power and driving pressure in children with pediatric acute respiratory distress syndrome.

Positive end-expiratory pressure (PEEP) is widely used to improve oxygenation and avoid alveolar collapse in mechanically ventilated patients with pediatric acute respiratory distress syndrome (PARDS). However, its improper use can be harmful, impacting variables associated with ventilation-induced lung injury, such as mechanical power (MP) and driving pressure (∆P). Our main objective was to assess the impact of increasing PEEP on MP and ∆P in children with PARDS. Mechanically ventilated children on pressure-controlled volume-guaranteed mode were prospectively assessed for inclusion. PEEP was sequentially changed to 5, 12, 10, 8, and again to 5 cm H2O. After 10 min at each PEEP level, ventilatory data were collected and then variables of interest were determined. Respiratory system mechanics were measured using the least squares fitting method. Thirty-one patients were included, with median age and weight of 6 months and 6.3 kg. Most subjects were admitted for acute viral bronchiolitis (45%) or community-acquired pneumonia (32%) and were diagnosed with mild (45%) or moderate (42%) PARDS. There was a significant increase in MP and ∆P at PEEP levels of 10 and 12 cm H2O. When PEEP was increased from 5 to 12 cm H2O, there was a relative increase in MP of 60.7% (IQR 49.3-82.9) and in ΔP of 33.3% (IQR 17.8-65.8). A positive correlation was observed between MP and ΔP (ρ = 0.59). Children with mild or moderate PARDS may experience a significant increase in MP and ∆P with increased PEEP. Therefore, respiratory system mechanics and lung recruitability must be carefully evaluated during PEEP titration.

Hidden conflicts? Revealing power mechanisms in collaborative governance for redeveloping heritage districts: The case of Dashilar, Beijing, China

ABSTRACT The redevelopment of Chinese heritage districts increasingly adopts collaborative approaches, raising concerns about power dynamics in these processes and their potential impact on resolving conflicts of interest through collaboration. This study establishes a multi-dimensional framework, examining arenas and sources of power to uncover power mechanisms and their impact on collaborative governance in the redevelopment of Dashilar, Beijing, China. Through ethnographic research, we found that institutionalized collaborative decision-making empowers participants to have the final say on relocation and renovation decisions. However, biased mobilization and discursive practices, with different sources of power utilized, affect collaborative processes and outcomes. Over time, collaborative decision-making results in elite control of Dashilar’s historic fabric and its subsequent gentrification. The government consolidates its power by controlling economic resources and influencing land use decisions. Crucial conflicts remain obscured, weakening the interests of residents and market actors. To understand power in collaborative governance, analysis must encompass both sources and arenas of power, transcending observable interactions within formal institutions to include informal practices.

StAlK: Structural Alignment based Self Knowledge distillation for Medical Image Classification

In the realm of medical image analysis, where challenges like high class imbalance, inter-class similarity, and intra-class variance are prevalent, knowledge distillation has emerged as a powerful mechanism for model compression and regularization. Existing methodologies, including label smoothening, contrastive learning, and relational knowledge transfer, aim to address these challenges but exhibit limitations in effectively managing either class imbalance or intricate inter and intra-class relations within input samples. In response, this paper introduces StAlK (Structural Alignment based Self Knowledge distillation) for Medical Image Classification, a novel approach which leverages the alignment of complex high-order discriminative features from a mean teacher model. This alignment enhances the student model’s ability to distinguish examples across different classes. StAlK demonstrates superior performance in scenarios involving both inter and intra-class relationships and proves significantly more robust in handling class imbalance compared to baseline methods. Extensive investigations across multiple benchmark datasets reveal that StAlK achieves a substantial improvement of 6%–7% in top-1 accuracy compared to various state-of-the-art baselines. The code is available at: https://github.com/philsaurabh/StAlK_KBS.

National Center for Health Statistics Data Linkage Program: Generating Synthetic Data to Support Tiered Access

The National Center for Health Statistics (NCHS) has a long-established data linkage program that links NCHS health survey data with vital and other administrative records to expand the analytic potential of both the survey and administrative data. Integrating survey and administrative data provides a powerful mechanism for creating policy-relevant data resources to support the examination of factors that can influence disability, chronic disease, health care utilization, morbidity, and mortality. However, data privacy concerns impact the accessibility of NCHS linked data and thus its utilization. Nearly all NCHS linked data files are available only through the NCHS and Federal Statistical Research Data Centers. To minimize this barrier to access, the NCHS Data Linkage Program is engaged in a pilot project to create NCHS' first public-use fully synthetic data files. This initiative supports Evidence Act requirements, including tiered access to federal data. The talk will include an overview of the steps taken to generate the synthetic linked data and provide a verification process to support its analytic utility. The talk will also include a summary of NCHS’ exploration of other privacy enhancing technologies to increase partnership and data access.

Lower Late Development Rate of Acute Respiratory Distress Syndrome in Patients with Lower Mechanical Power or Driving Pressure.

For patients on ventilation without acute respiratory distress syndrome (ARDS), there are, as yet, limited data on ventilation strategies. We hypothesized that driving pressure (DP) and mechanical power (MP) may play key roles for the late development of ARDS in patients without initial ARDS. A post hoc analysis of a database from our previous cohort was performed. The mean DP/MP was computed from the data before ARDS development or until ventilator support was discontinued within 28 days. The association between DP/MP and late development of ARDS within 28 days was determined. One hundred and twelve patients were enrolled, among whom seven developed ARDS. Univariate Cox regression showed that congestive heart failure (CHF) history and higher levels of mean MP and DP were associated with ARDS development. Multivariate models revealed that the mean MP and mean DP were still factors independently associated with ARDS development at hazard ratios of 1.177 and 1.226 after adjusting for the CHF effect. Areas under the receiver operating characteristic curves for mean DP/MP in predicting ARDS development were 0.813 and 0.759, respectively. In conclusion, high mean DP and MP values may be key factors associated with late ARDS development. The mean DP had a better predicted value for the development of ARDS than the mean MP.

Prophecy And Reality: Hegemony In “1984” George Orwell And “Entrok” By Okky Mandasari

This study investigates the hegemonic practices depicted in George Orwell’s “1984” and Okky Mandasari’s “Entrok,” comparing the methods of state control and indoctrination in both novels. Hegemony, as conceptualized by Gramsci, involves not just physical dominance but also ideological influence and societal consensus. This research employs a qualitative inductive method to explore how these novels represent state hegemony through their narratives and characters “1984” portrays a dystopian society where The Party exerts total control, influencing citizens from childhood through public spectacles and constant surveillance, leading to pervasive fear and compliance. Similarly, “Entrok” depicts the New Order era in Indonesia, where the state employs indoctrination intimidation to maintain power, affecting individuals and their communities. Through comparative literature theory, this study highlights the similarities and differences in the portrayal of state dominance in these two novels. The findings reveal that both novels illustrate the pervasive and multifaceted nature of hegemony, emphasizing the role of ideological control and the subtle mechanisms of power that shape societal behavior and beliefs.

Waqf Business Model (WBM): Towards A Sustainable Social Business Model on The Mainstream Economics

The Waqf Business Model (WBM) represents an innovative and transformative approach to establishing a sustainable social business model within mainstream economics, rooted in Islamic economic principles. This paper explores the current state of waqf as an alternative model for social business, emphasizing its ability to combine social impact with long-term economic sustainability by preserving assets and generating ongoing revenue. It also advocates for integrating WBM into the mainstream economy to serve as a powerful mechanism for addressing the Sustainable Development Goals (SDGs). The paper highlights the challenges faced by traditional Islamic economic institutions, particularly waqf, which have struggled due to outdated management practices and a conceptual crisis regarding the role of waqf in modern economies. Revitalizing waqf institutions requires enhancing their capabilities and aligning them with contemporary business strategies. Additionally, this paper encourages future research to explore how WBM can be fully integrated into the existing economic ecosystem. In theory, WBM provides a framework for ethical and inclusive economies, while in practice, it has the potential to create self-sustaining institutions that reduce reliance on external aid, offering an innovative solution to global socio-economic challenges by blending sustainable innovation.

Low temperature rotary Stirling engine: Conceptual design and theoretical analysis

The use of low-temperature energy sources for electricity generation demands a dual focus: a substantial enhancement in the efficiency of energy conversion devices and a reduction in system production costs. Particularly in scenarios where low-temperature energy sources are scarce, this factor can be pivotal in facilitating widespread adoption of such technologies. The Stirling engine emerges as a promising solution capable of meeting these articulated expectations, owing to its straightforward design and utilization of non-toxic, non-flammable, and cost-effective working mediums. This paper introduces a novel concept of a rotary Stirling engine, exhibiting significant potential for operation with low-temperature energy sources. Additionally, an analytical model of the engine is presented, enabling simulations of its operation under varying supply temperatures and geometric configurations. To analyse the impact of internal leaks on the net efficiency and net power of the engine, a modified adiabatic model was introduced. It was observed that utilizing identical heat exchangers for heat supply at 250 °C and 100 °C could lead to a decline in net efficiency from 8 % to 3 % for the worst case. Furthermore, an analysis was performed to assess the impact of the heater’s overall heat transfer coefficient and engine rotational speed on both net efficiency and net mechanical power for a heat supply temperature of 200 °C.

‘No sword could ever pierce my heart more than when I must miss my child’: Power dynamics, agency and motherhood in the prison of ‘s‐Hertogenbosch 1820–1880

AbstractUsing a microhistorical lens on the prison of ‘s‐Hertogenbosch in the Netherlands, this article focuses on practices and regulations concerning mothers and children and ideas about motherhood and practices of care to show how different powers intersected and were ‘at work’ within the prison. Analysing the decision‐making, discourses and practices the authorities used to exert power over criminalised women and their children, this article argues that the prison policy was not designed to care for or protect mothers and children. On the contrary, it led to the deaths of many infants incarcerated with their mothers. Moreover, it paradoxically deprived incarcerated women of one of the pillars of nineteenth‐century bourgeois femininity: motherhood. The mothers, however, actively resisted and negotiated the prison's power mechanisms to create opportunities to care for their children and influence their fate.

Statistical Learning Facilitates Access to Awareness

Statistical learning is a powerful mechanism that enables the rapid extraction of regularities from sensory inputs. Although numerous studies have established that statistical learning serves a wide range of cognitive functions, it remains unknown whether statistical learning impacts conscious access. To address this question, we applied multiple paradigms in a series of experiments (N = 153 adults): Two reaction-time-based breaking continuous flash suppression (b-CFS) experiments showed that probable objects break through suppression faster than improbable objects. A preregistered accuracy-based b-CFS experiment showed higher localization accuracy for suppressed probable (versus improbable) objects under identical presentation durations, thereby excluding the possibility of processing differences emerging after conscious access (e.g., criterion shifts). Consistent with these findings, a supplemental visual-masking experiment reaffirmed higher localization sensitivity to probable objects over improbable objects. Together, these findings demonstrate that statistical learning alters the competition for scarce conscious resources, thereby potentially contributing to established effects of statistical learning on higher-level cognitive processes that require consciousness.

Squeeze force of a Maxwell fluid between circular smooth surfaces with simple harmonic motion

The force and mechanical power required to maintain the simple harmonic motion (SHM) of the upper circular surface squeezing a viscoelastic fluid film is analyzed. The amplitude of the displacement of the upper surface is very small compared to the gap width as a function of time. The smoothness of the upper and lower surfaces is characterized by the slip model with two constant parameters, a slip length and a critical surface shear stress. The nonlinear convection terms in the momentum equation are neglected since the viscous forces dominate the inertial forces. The acceleration and deceleration terms are retained since the upper plate oscillates harmonically and the velocity in the fluid is strictly periodic. An exact solution of the governing equations is found as a function of the Deborah number, the Womersley number, the slip length, and the critical surface shear stress. A circular region without slip condition, bounded by a time-dependent radius, appears when the shear stress of the fluid does not exceed a critical surface shear stress. In addition, an annular region with slip up to the radius of the disk appears when the critical surface shear stress is exceeded. Our results show that viscoelastic and hydrophobic effects together with the Womersley number and a critical surface stress cause changes in the amplitude and phase lag of the waveform of the time-dependent radius and the force acting on the wall surface to maintain the SHM of the upper disk.

A Comparison of a Three Blade and Five Blade Wind Turbine in Terms of the Mechanical Properties Using the Q-Blade Software

يمكن لتوربينات الرياح المنتشرة في مزارع الرياح على نطاق المرافق أن تدعم تلبية رغبات الطاقة المستقبلية وتقليل انبعاثات ثاني أكسيد الكربون عن طريق تقليل متطلبات الطاقة من الوقود الأحفوري. مع ارتفاع درجة حرارة الهواء على مدار اليوم، تزداد سرعة الرياح بسبب تدرجات درجة الحرارة، والتي تنتج تدرجًا في الكثافة / الضغط، مما يؤدي إلى حركة الهواء التي تواجهها توربينات الرياح. اعتمادًا على تضاريس الأرض، يمكن أن تواجه الرياح وتوجه في الوديان بين التلال وفوقها حيث تتدفق وتتبع منحنيات الأرض. تنتج هذه التضاريس زيادة في سرعة الرياح في القمم والتلال. في هذا العمل، تم تصميم شفرة دوار توربينات الرياح الأفقية الصغيرة للعمل في ظل سرعة الرياح المنخفضة، باستخدام برنامج (Q-Blade). استنادًا إلى نظرية عنصر الشفرة (BEM). مع الجنيح NACA3712. تم استخدام دوار ثلاثي الشفرات ودوار بخمس شفرات بناءً على نوع التوربين وحجم الدوار لتوليد الطاقة الميكانيكية من طاقة الرياح. تم إجراء مقارنة وتحليل قوة التوربين ومعامل القدرة ومعامل عزم الدوران عند سرعة رياح منخفضة ((1m/s-8m/s وتم الحصول على نتائج دقيقة للغاية. وجد أن أفضل أداء يمكن أن يعمل فيه دوار توربيني ثلاثي الشفرات بقدرة توربينية تبلغ (955W) كما تم الحصول على قدرة التوربين ((582W للدوار خماسي الشفرات. وجد أن تصميم توربينة رياح أفقية صغيرة بخمس ريش أفضل من التوربين بثلاث ريش ومناسب للعمل في المناطق ذات سرعة الرياح المنخفضة وبكفاءة عالية مقارنة بحجم التوربين.