Theoretical Angle Research Articles

Anthropomorphic modular gripper finger actuated by antagonistic wire and shape-memory alloy (SMA) springs

Abstract. The traditional underactuated grippers can only passively adapt to the contour of the object, and the passive contact process may lead to the object slipping, affecting the stability of the grasping process. In this paper, an anthropomorphic modular gripper finger actuated by antagonistic wire and shape-memory alloy (SMA) springs, which can actively control the grasping morphology according to the characteristics of the objects to be grasped, is proposed. The wire drive simulates the flexor muscle, and the SMA and reset springs simulate the extensor muscles of the finger, which antagonistically control the grasping morphology of the finger. It is more in line with the grasping characteristics of the human hand. According to the moment equilibrium principle of the finger joints, the deformation model of the gripper is established, the influence of the wire tension and the equivalent stiffness of the finger joints on the grasping morphology is analyzed, and the theoretical joint angle results are verified by the Adams simulation; finally, the experimental system of the gripper is constructed, and the verification of the deformation morphology of the single finger and the gripper's enveloping–grasping experiments is completed. The results show that according to the contour size of the object, by actively controlling the wire force of the gripper and the equivalent stiffness of the interphalangeal joints, the enveloping–grasping action of different objects can be completed and the stable grasping of objects of different shapes and sizes can be realized.

Ambivalent citizenship: political cynicism, community engagement and belonging among youth in Brazil

ABSTRACT This article interrogates the role of urban peripheries in creating political imaginaries and understandings of citizenship among children and grandchildren of insurgent citizens in urban Northeast Brazil. The analysis draws on data collected through 10 ethnographically informed focus groups with youth between 18 and 35. The article argues that, contrary to beliefs that young people are apathetic about politics or enthusiastic to engage in progressive social movements, youth have an ambivalent relationship with the state, informed by everyday encounters with precarious infrastructure, awareness of previous forms of collective action that determines their civic engagement, and feelings of belonging to home communities. The article suggests revisiting the concept of insurgent citizenship considering new socio-political changes that framed the lives of young people living in urban peripheries in the past two decades in Brazil and proposes ambivalence as a productive theoretical angle to make sense of ruptures and discontinuities in political practices.

A novel radiographic finding for estimation of the cortical-cancellous boundary: A magnetic resonance imaging case series of patients with femoroacetabular impingement

PurposeTo determine if comparing alpha angle measurements of the outer cortical margin (preoperative alpha angle) and the inner cortical margin (theoretical postoperative alpha angle) on magnetic resonance imaging (MRI) can estimate the amount of sclerotic bone that needs to be resected to restore the alpha angle to normative values (<55⁰) in patients with symptomatic femoroacetabular impingement (FAI). MethodsA retrospective review was conducted on patients with FAI undergoing primary hip arthroscopy and CAM osteoplasty from June 2013 to February 2017. Inclusion criteria were radiologist-measured alpha angles >70° on 3T oblique axial MRI, unilateral primary hip arthroscopy, and age ≥18. Exclusions included previous hip surgery, hip trauma, avascular necrosis, advanced osteoarthritis, dysplasia, poor quality images, or missing MRI images. Alpha angles were measured preoperatively using the outer cortical margin and postoperatively using the inner cortical margin of femur. Surgeries were performed by the senior surgeon. Paired t-tests compared preoperative and postoperative alpha angles, and intraclass correlation coefficients (ICC) were used to assess inter-rater and intra-rater reliability. ResultsOne hundred patients (100 hips) were included with an average age of 40.8 years (range, 18.7–64.9), with 75 % being male (n = 75). The average BMI was 24.7 ± 3.9 (range, 17.1–38.8). The average maximum alpha angle at the outer cortical margin was 77.0 ± 4.2° (range, 70.0–90.8), with an ICC for inter-rater reliability of 0.861, indicating excellent agreement. The average inner cortical alpha angle was 46.4 ± 3.4° (range, 36.5–55.4), significantly less than 55° (p<0.001). The mean difference between the outer and inner cortical alpha angles was −30.6 ± 5.1° (p< 0.001). ConclusionsThe difference between outer and inner cortical alpha angles on MRI can accurately estimate the amount of sclerotic bone resection needed to restore the alpha angle to normative values in patients with FAI. This information may be directly applied clinically marker to assess adequacy of CAM resection.

Analysis of Atomization Performance of Linear Laval Nozzle under Varied Water Pressures Based on VOF and DPM Models

Particulate matter from coal and stone operations is a primary air pollution source. The traditional nozzle requires high-pressure conditions, and the atomization droplets are large and uneven. This paper aims to study a linear Laval nozzle and investigate the impact of water pressure on atomization performance. The volume of fluid (VOF) model and discrete phase model (DPM) of Fluent are used to simulate the internal and external fields of the nozzle and analyze the velocity, droplet size, and atomization angle. The results show that the optimized water pressure parameters are 0.1 MPa with an air pressure of 0.5 MPa. Droplets in the middle are smaller, while those on the sides are larger. Compared to traditional nozzles, the water pressure is reduced by over 90%, and the Sauter mean diameter (SMD) decreases by over 50%. Moreover, the theoretical spray angle increases by approximately 150%.

Steering the Atoms for Peace and Development: Legal Aspects of the Board of Governors of the International Atomic Energy Agency

International Atomic Energy Agency (IAEA) is the leading international organization in the field of nuclear energy and nuclear non-proliferation. This paper examines the most important policy body of the Agency, the Board of Governors (BoG). The legal foundation of the BoG will be discussed in light of its constitutional documents, most notably the Statute of the IAEA and the Rules of Procedure of the BoG. The research question will be approached from the theoretical angle of functionalism. The paper suggests that in fact, the practical role of the BoG is even more important than could be concluded on the basis of the legal documents whence the powers of the BoG derive. Over the years, the normative framework of the IAEA has enabled the BoG to adapt to rapidly changing decision-making environments and political situations. Furthermore, this has made it possible for the BoG to contribute in a relatively effective manner to the development of substantive international nuclear policy and law.

Fuzzy-pid control design of biped robot based on motion capture technology

Abstract To improve the precision of the biped robot’s walking control system, a fuzzy PID controller with a variable theory domain was added to the design of the biped robot’s lower limb control system to optimize the tracking process of joint angular displacement and improve the motion effect. Firstly, the motion capture experiment is carried out to obtain the angular displacement data of the joint. The theoretical angle was calculated according to the biped robot’s lower limb diagram model and kinematics equation, and the expected trajectory was obtained by simple gait planning and using MATLAB to verify the validity of the angle parameters. Then the fuzzy PID controller of the lower limb joint was established, and the variable theory domain fuzzy controller was established by introducing the expansion factor. Finally, the Simulink test bench is built to simulate the two controllers, and the expected data and simulation data are compared. The results show that the error range of the variable theory domain fuzzy controller is only ±2°, and the variable theory domain adaptive fuzzy controller can accurately track the desired trajectory, reduce the joint angular displacement error of the biped robot, ensure the precision and stability of the biped robot motion, and basically meet the requirements of practical production.

The effect of forming surface interference on Thin-Walled profiles during the discontinuous forming process with discrete molds

This study aims to investigate the influence of the roller dies’ characteristics of shapes on the forming results in the roller-based flexible multi-point three-dimensional stretch bending forming (FSBRD) process for thin-walled profiles, as well as the prediction of mold-induced impressions during the FSBRD process. Considering the specific contact mode, an L-shaped section profile’s flange was selected as the research object to analyze the impact of the roller dies’ slot’s geometric parameters on the product. A classification model of the contact between the profile’s flange and the roller die was established for the vertical bending process, and the maximum theoretical interference value (imax) was calculated to predict the extent of local deformation after contact. Subsequently, finite element software was used to model the process and analyze the changes in equivalent plastic strain (PEEQ) of the deformation results when using roller dies with slots of different parameters, including straight, inclined, and arc-shaped slots. The analysis results indicate that the width of the straight slot has a significant influence on the forming quality of the product, as a smaller slot width leads to larger local dimples on the product surface. Replacing the straight slot with an inclined or arc-shaped slot improves the abrupt changes in local PEEQ, resulting in reduced macroscopic local dimples. The simulation results align with the analytical model’s variation of imax. This study defined the theoretical contact angle γ and introduced the concept of the contact area and the local theoretical interference zone, providing a reasonable explanation for the observed PEEQ variations. Furthermore, based on the conclusions of the research above, modified experiments were designed, resulting in favorable forming effects. The validation of the simulation results was performed by comparing the local dimples in the contact zone of the actual experimental results.

Lattice destabilization in electron-beam-irradiated antimony in TEM

This study investigates the effect of electron-beam heating in transmission electron microscopy (TEM) on the structure of antimony (Sb) thin films. TEM of Sb irradiated with 300 keV electrons reveals a significant deviation (2–3°) from the theoretical interplanar angle between certain planes within the irradiated region. We relate this anomaly to electron-beam heating under electron-beam irradiation. Our FEA simulations reveal localized heating within the irradiated region caused by Auger electron excitation. These simulations predict temperatures as high as 949 K, accompanied by ultrafast heating and quenching rates. This extreme thermal cycling likely induces significant thermal stress in localized regions, possibly exceeding their elastic limits. This stress is likely related to the observed structural anomalies. This work highlights the importance of considering beam heating, particularly when interpreting TEM data from nanoscale materials with reduced thermal conductivity due to surface scattering effects.

Exploring in-plane shear characteristics of multilayer biaxial weft knitted fabrics through a micro-scale virtual fiber modeling

The multilayer biaxial weft knitted (MBWK) fabrics and their composites have been widely applied in fields of complex structural products due to their flexible curved deformability. The existence of stitch in MBWK complicates the deformation behavior under the in-plane shear loading. However, it has not been well explored and understood. In this study, a numerical micro-scale virtual fiber modeling was built to investigate the in-plane shear performance of MBWK by considering the micro geometric features and fiber property that are difficult to be characterized solely by experiment. The strain conditions of the stitch that determine the fabric shear behavior are discussed. The deformation behavior leads to local deformation and morphological locking of the stitch. In the early stage of the shearing, the deformability of stitch provides enough space to accommodate the rearrangement of axial yarns. In the shear locking stage, the restriction of stitch and compression within axial yarns at high shear angles restricts the axial yarns from movement in the loading direction. When the theoretical shear angle is 20°, the shear angle located in different shear regions varies. The maximum shear angle near the loading area is 19.1°, while the minimum shear angle near the fixed area is approximately 17°. The results illustrate the deformation mechanism of MBWK under in-plane shearing and provide an excellent guidance for the design of large deformation fabrics, especially for curved surfaces, thus realize the effective utilization of fabrics in engineering applications.

Bending of Light by Magnetars within Generalized Born–Infeld Electrodynamics: Insights from the Gauss–Bonnet Theorem

We compute the weak bending angle of light within generalised Born–Infeld electrodynamics as it passes through the equatorial plane of a magnetic dipole. We start by considering the refractive index associated with the dipole within generalised Born–Infeld electrodynamics. Then, we calculate the Gaussian optical curvature based on these refractive indices. Using the Gauss–Bonnet theorem, we derive a formula to quantify the deflection angle in the presence of a strong magnetic field from a dipole. Our results align with results obtained through traditional geometric optics techniques, underscoring the importance of the Gauss–Bonnet theorem as a versatile tool for solving intricate problems in modern theoretical research. We apply our theoretical deflection angle formula to estimate the light bending in magnetars listed in the McGill catalogue, providing insights into the behaviour of light in environments with strong magnetic fields.

Optimization and experimental validation of reinforcing fibers winding pattern for carbon/carbon composite crucible preform

In order to address the problem of transition slip between the cylindrical segment and the ellipsoidal head segment of the carbon/carbon composite crucible preform with asymmetrical structure during the winding process, a winding pattern combining geodesic and non-geodesic is presented innovatively. Firstly, the formulae for the winding angle and the winding central rotation angle of the crucible cylindrical segment and the ellipsoidal head segment are established, and the fourth-order Runge-Kutta numerical method is employed for parametrical design. The two-tangent point winding path is determined by analyzing the effect of the cylindrical segment’s winding pitch, different ellipsoidal head segment heights, and slip coefficient on the winding angle. Secondly, the needle disk winding method is proposed to address the slight winding angle at the open end of the cylinder, making it easier to hang the yarn. Finally, the experiment on dry yarn winding of 3k carbon fiber (linear density: 198 g/km) is carried out. The results indicate that the relative error rate between the actual winding angle and the theoretical design angle differs by no more than 1.66%, demonstrating that carbon fibers can be stably and uniformly wound onto the surface of the carbon/carbon composite crucible preform. Compared to the traditional manual winding method, the winding pattern enhances winding efficiency, ensures carbon fibers’ uniformity and structural stability, and provides a new technological approach to producing high-performance composite materials.

Does board’s green theme training promote green innovation? A view from resource dependence perspective: Indonesian evidence

PurposeThe study has practical implications for decision-makers in that increasing board competence and expertise through training on environmental issues will promote green policy-making.Design/methodology/approachThis study included 655 firm-year observations from companies listed on the Indonesia Stock Exchange between 2017 and 2021. Panel data regression analysis is used to investigate the hypotheses. Additionally, a robustness test is conducted to validate the consistency of the primary test results.FindingsThe results demonstrate that green theme training from the board of directors, board of commissioners and independent commissioners has a positive and significant impact on the implementation of green innovation at each level of the board. This result is aligned with the robustness test performed.Research limitations/implicationsThis study is restricted by the fact that the only data sources used to examine the board’s green training are publication reports and other reports that disclose the board’s training activities. Therefore, future research can be done by considering other methods, such as surveys to trace green training followed by the board. Additional research may also examine green theme training in the corporate governance structure from a different theoretical angle, such as agency theory and human capital theory.Practical implicationsIn practice, the study has implications for decision-makers in that increasing board competence and expertise through training on environmental issues will be able to promote green policy-making.Originality/valueThis study concentrates on Indonesia with two-board governance characteristics: the board of directors and the board of commissioners. Several scholars have examined the board of directors in light of resource dependence theory. To the best of the authors’ knowledge, no research has explained the supervisory board within the context of two-board governance. In addition, the authors have not found research that analyzes board training activities related to the environment.

Optimal Tilt Angle of Photovoltaic Panels: A Case Study in the City of Rio de Janeiro

The optimal tilt angle of photovoltaic panels plays a crucial role in energy generation. However, the accumulation of dust on solar panels can significantly impact their performance and efficiency, leading to a reduction in energy production. Therefore, it is crucial to consider the effect of dust deposition on the optimal tilt angle of solar panels. Regarding panel installation, it is often observed that panels are positioned to follow the natural slope of the roofs, disregarding the optimal angle for maximizing solar radiation utilization. Numerous studies have investigated the impact of dust accumulation on the performance of photovoltaic panels and the optimal inclination angle for different regions and seasons. This study aims to analyze the optimal tilt angle of photovoltaic panels for maximum energy generation, considering undesired effects such as dust, dirt, water droplets, and other atmospheric factors. The authors have proposed an equation to calculate the optimal tilt angle of photovoltaic panels based on a case study conducted in different Rio de Janeiro City regions. The methodology employed in this study involves estimating solar incidence on the surface of the photovoltaic panels using the authors' proposed equation, which considers the latitude and longitude of the panel installation location. The results obtained were validated using software that generates hourly solar radiation data. The results indicate that an inclination of 30 degrees, calculated using the proposed equation, resulted in a 2% deviation from the optimal theoretical angle.

Developing a Novel Advance Planning Tool for Dementia Patient Participation in Scientific Research.

AbstractResearch represents an avenue through which patients can contribute to the knowledge base surrounding their condition. However, persons with dementia cannot legally consent to participation in most scientific research. One possible avenue to preserve patient autonomy in the sphere of research is through an advance planning document. Scholars of medicine, ethics, and law have largely approached this topic from a theoretical angle, compelling the authors to develop and implement a tangible research-specific advance planning tool. In order to inform the creation of this novel legal instrument, the present study leveraged semistructured telephone interviews with cognitively intact older adults in the Upper Connecticut River Valley region of New Hampshire. Participants were prompted to reflect on their attitudes toward participation in scientific research, should they develop dementia. They were also asked to consider the possibility of incorporating research into their advance planning regime, their preferred format for a research-specific advance planning tool, and the potential relationship between an advance planning tool and their surrogate decision maker in the context of research participation. Qualitative analysis was employed to extract themes from interview responses, revealing a pervasive desire for an advance planning tool that embraces specificity, flexibility, practicality, and the integral role of the surrogate decision maker. Ultimately, through collaboration with physicians and an elder law attorney in the region, these findings were translated into a research-specific advance planning component within the Dartmouth Dementia Directive.

Three-Point Bending Test and Finite Element Simulation Study of 304 Stainless Steel Based on Elastoplastic Constitutive Model

Rebar bending is commonly found in engineering and has received widespread attention. In this paper, a combination of experimental and finite element methods was used to conduct a study on three-point bending of 304 stainless steel. The real-time bending angle of the round bar during bending was recorded using a digital inclinometer. The force-displacement curves of specimens with different diameters were obtained and compared with the results of finite element simulations. Furthermore, the results from the digital inclinometer were compared with theoretical angle values. The findings suggest that the larger the diameter of the 304 stainless steel round bar, the greater the normal force it experiences. The finite element results are relatively consistent with the experimental results. The angle displayed by the digital inclinometer is consistent with the theoretical angle value of the round bar before unloading. The rebound angle of the reinforcing bar is greatly influenced by its diameter. When the diameter of the round bar exceeds a certain value, the rebound angle can be neglected.

Octonion Internal Space Algebra for the Standard Model

This paper surveys recent progress in our search for an appropriate internal space algebra for the standard model (SM) of particle physics. After a brief review of the existing approaches, we start with the Clifford algebras involving operators of left multiplication by octonions. A central role is played by a distinguished complex structure that implements the splitting of the octonions O=C⊕C3, which reflect the lepton-quark symmetry. Such a complex structure on the 32-dimensional space S of Cℓ10 Majorana spinors is generated by the Cℓ6(⊂Cℓ10) volume form, ω6=γ1⋯γ6, and is left invariant by the Pati–Salam subgroup of Spin(10), GPS=Spin(4)×Spin(6)/Z2. While the Spin(10) invariant volume form ω10=γ1…γ10 of Cℓ10 is known to split S on a complex basis into left and right chiral (semi)spinors, P=12(1−iω6) is interpreted as the projector on the 16-dimensional particle subspace (which annihilates the antiparticles).The standard model gauge group appears as the subgroup of GPS that preserves the sterile neutrino (which is identified with the Fock vacuum). The Z2-graded internal space algebra A is then included in the projected tensor product A⊂PCℓ10P=Cℓ4⊗Cℓ60. The Higgs field appears as the scalar term of a superconnection, an element of the odd part Cℓ41 of the first factor. The fact that the projection of Cℓ10 only involves the even part Cℓ60 of the second factor guarantees that the color symmetry remains unbroken. As an application, we express the ratio mHmW of the Higgs to the W boson masses in terms of the cosine of the theoretical Weinberg angle.

Surviving the unprecedented: family firms under COVID-19

PurposeThe purpose of this study is to examine factors contributing to family firms’ survival in the ongoing COVID-19 crisis; in this endeavour, the study espouses the underpinnings of social exchange theory and entrepreneurial resilience.Design/methodology/approachThe views of 128 Italian family micro and small-sized firm owners/managers operating in different industries were gathered through an online questionnaire.FindingsThe analysis uncovers 12 fundamental factors contributing to firms’ survival; these are encapsulated in three dimensions and presented in two theoretical frameworks. The “beneficiary” dimension stresses the support from various internal and external stakeholders, while the “benefactor” dimension illustrates the commitment to extend the family tradition and be responsive to stakeholders. Finally, the “immersion/embeddedness” dimension denotes firms’ entrepreneurial behaviour, agility, decision-making and drive.Originality/valueFirstly, and from a practitioner perspective, this study addresses recognised knowledge and research gaps in contemporary family business research, including how family firms are confronting the current unprecedented crisis. This response to current extant gaps provides first-hand empirical findings that could be primarily considered by industry stakeholders. Secondly, and from a theoretical angle, the aforementioned dimensions revealed through the analysis, coupled with the development of a theoretical framework, contribute to conceptual rigour and, therefore, a deeper understanding of family firms’ journey through an unprecedented event.

Calibrate the non-orthogonal error of AFM with two-dimensional self-traceable grating

The calibration of the non-orthogonal error in nanoscale measurements is of paramount importance for analytical measuring instruments. Particularly, the calibration of non-orthogonal errors in atomic force microscopy (AFM) is essential for the traceable measurements of novel materials and two-dimensional (2D) crystals. The 2D self-traceable grating with a theoretical non-orthogonal angle of less than 0.0027° and an expanded uncertainty of 0.003° (k = 2) are measured by the Metrological Large Range Scanning Probe Microscope (Met. LR-SPM). In this study, we characterized the local and overall non-orthogonal error in AFM scans and proposed a protocol to tune the optimal scanning parameters of AFM minimizing the non-orthogonal error. We presented the method for accurately calibrating a commercial AFM system for non-orthogonal by establishing a detailed uncertainty budget and errors analysis. Our results verified the important advantages of the 2D self-traceable grating in calibrating precision instruments.

Spectacle measurements versus contact lens measurements of the angle of deviation in myopic patients with strabismus

Purpose To compare the measurements of the angle of deviation through spectacles versus contact lenses and with the theoretically calculated angle. Patients and methods A total of 20 patients with comitant strabismus, more than 20 PD with spectacles, associated with bilateral myopia (spherical equivalent &gt;1 D in both eyes) were included. Angle of deviation was measured using prism and cover test with spectacles and with contact lenses fitted according to the cycloplegic refraction and refined by subjective refraction. Agreements between the measurements obtained with contact lenses and those obtained with spectacles as well as the theoretically calculated angle were analyzed. Results The mean age was 15.6±10.9 years. Average spherical equivalent was −9.1±4.2 D. Measurements obtained with contact lenses were significantly lower than those with spectacles (P&lt;0.001) with coefficient of variation of 27.7%, indicating poor agreement of both measurements. Limits of agreement in Bland–Altman plots were more than 9 PD (d ± 2 s, −8.8 to 6 PD). The agreement was lower with larger angles. Measurements obtained with contact lenses were significantly lower than theoretical angles (P=0.002) but coefficient of variation between both measurements was 8.8%, indicating good agreement of measurements. There was little systematic or proportionate bias between the contact lens measurements and the theoretical angle. Conclusions Contact lens measurements were significantly lower than spectacle measurements in myopic patients. The contact lens measurements were in good agreement with the theoretically calculated angle. This overestimation of the angle with spectacles might be responsible for overcorrection of myopic patients with exotropia after surgery.

Clinical application of a quantitative method of atlantoaxial reduction angle in basilar invagination

Objectives: To investigate the clinical application effect of a quantitative method of atlantoaxial reduction angle in basilar invagination. Methods: A retrospective analysis of clinical and radiographic data was conducted of 38 patients with complicated atlantoaxial dislocation and basilar invagination admitted to the Department of Neurosurgery, First Affiliated Hospital of Chongqing Medical University from May 2020 to May 2022. There were 5 males and 33 females, aged (53.5±9.9) years (range: 38 to 80 years). All patients underwent C1-2 interarticular fusion cage implantation+occipital-cervical fixation by pressing rob with the cantilever technique. The atlantoaxial reduction model of previous studies by our team was used to calculate the reduction angles before surgery. Then titanium rods of prebending angle were prepared according to the calculation before the operation. After that quantitative reduction of angle was performed during the operation. The paired t-test was used to compare the difference between the theoretical and actual reset value. Results: The theoretical reduction angle of all patients was (10.62±1.78)° (range: 6.40° to 13.20°), the actual reduction angle was (10.53±1.63)° (range: 6.70° to 13.30°) and there was no statistical difference between them (t=1.688, P=0.100). The theoretical posterior occipitocervical angle after the operation of all patients was (117.37±5.88)° (range: 107.00° to 133.00°), the actual posterior occipitocervical angle after the operation was (118.25±6.77)° (range: 105.40° to 135.80°) and there was no statistical difference between them (t=-0.737, P=0.466). The postoperative follow-up time of the patients was more than 6 months and the symptoms of all patients were relieved. All patients had satisfactory fusion between small joints without incision infection, internal fixation fracture, displacement, atlantoaxial redislocation, and other long-term complications. Conclusion: The quantitative method of atlantoaxial reduction angle in basilar invagination can calculate the theoretical reduction angle of the clivus axis angle and guide the preparation of the pre-bending titanium rod before surgery, so as to realize the quantification of the atlantoaxial reduction angle.