Coercivity Mechanism Research Articles

Exclusion Despite Nominal Inclusion: A Critical Analysis of Participatory Development Programmes in Post‐War Colombia

Citizen participation takes centre stage in Colombia's 2016 peace agreement. Its practical implementation, however, has proven difficult. This case study examines targets and tactics of exclusion in participatory development programmes established under the peace accords. Drawing on qualitative data generated between 2021 and 2022 in the Sierra Nevada de Santa Marta, this article argues that exclusion affects societal (sub‐)groups, organisations and communities as a whole and involves a large array of implicit‐elusive, direct‐explicit and coercive mechanisms. This matters for implementing inclusive peacebuilding more generally.

How are family businesses involved in the organizational network of the Communist Party of China: the perspective of organizational sociology

Embedding its own branches in private enterprises is the governance strategy that the Communist Party of China (CPC) controls the grassroots society. This study proposes a framework by incorporating the socioemotional wealth theory into neo-institutionalism to explain how are family businesses involved in the organizational network of the CPC. Findings reveal that there is an organizational isomorphism that the coverage of party organizations expanded from non-family businesses to family businesses. Furthermore, family businesses are not likely to establish party organizations when coercive pressures are low. However, this resistance strategy sharply disappears when coercive pressures are high, and joining state-backed industry associations and mimicking others’ practice both are also positive factors motivating family businesses to establish party organizations, which means that the coercive, normative and mimetic mechanisms jointly shape the organizational isomorphism. This study contributes to the literature of neo-institutionalism and sheds new light on the state-society relationship in China.

Student evaluation of teaching and student centeredness in the Humboldtian and Emirati tribal traditions of higher education

ABSTRACT This study is the result of interviewing administrators and academics as well as conducting content analysis of student evaluation of teaching (SET) forms in 14 universities in Germany and the United Arab Emirates (UAE). The aim was to establish whether and if so, how, this procedure differs in two highly hierarchical social and academic contexts. We found that SETs have been adopted by all the universities we visited between 2001 and 2013, for some courses in Germany and for all of those in the United Arab Emirates. National and regional higher education laws and accreditation procedures act as coercive and normative mechanisms that promote SET’s implementation in Germany and the UAE, respectively. It emerged that SETs are commonly used for monitoring in Germany and the UAE, in private Emirati and German universities for checking the continuity of contracts and, in private German ones, to report students, while Emirati students do not receive reports, despite their treatment as clients. Further, we elicited that SETs reproduce student-centeredness in all the visited universities in both countries, albeit to varying degrees. We conclude that SETs demonstrate the strength of rationalizing trends in higher education (HE). Moreover, nuances in the implementation of SET, which we relate to the protection of professors’ autonomy in Germany and the cultural norm of respecting faculty as a highly regarded position in the UAE, remain related to the Humboldtian and tribal heritage of our studied countries, respectively.

Coercive and mimetic isomorphic mechanisms for service provision: The creation of nonprofit organizations in Mexico before and during the COVID-19 pandemic

Nonprofit organizations represent diverse efforts of collective action and service provision, and have for some time been collaborators to public governance systems in developed and developing economies. In this article, we contribute to the limited empirical and analytical study in the field of public policy and administration about the operational environments that enable or constrain nonprofits in the provision of public goods and services. The operational environment for organized civil society, namely for nonprofits, includes the combination of their regulatory, political, and funding contexts. By analyzing the purposes of 296 new nonprofits registered between 2016 to 2020 in Mexico, the empirical context of our inquiry, we find that as resources have declined, new nonprofits adopt isomorphic mechanisms by resembling their purposes to the services the government intends to support. Nonprofits have also responded to the pandemic by focusing more than before on areas related to health, social assistance, and funeral services. The study contributes to bigger questions about the relationships between and balance across the responsibilities of governments and nonprofits, including during the COVID pandemic, and to the understanding of nonprofits as service providers in public governance.

Electrical detection of domain evolution in magnetic Weyl semimetal Co3Sn2S2 submicrometer-wide wire devices

Microscopic understanding of magnetization switching via domain nucleation and/or domain-wall propagation is fundamental knowledge for developing magnetic and spintronic devices. Here, we explore the underlying mechanism of the large coercivity of the magnetic Weyl semimetal ${\mathrm{Co}}_{3}{\mathrm{Sn}}_{2}{\mathrm{S}}_{2}$ thin films, which is roughly ten times larger than that of ${\mathrm{Co}}_{3}{\mathrm{Sn}}_{2}{\mathrm{S}}_{2}$ bulk single crystal, by measuring Hall resistance in constricted wire devices. The discretized steplike variations appear in the hysteresis loops of the Hall resistance in $0.6\phantom{\rule{4pt}{0ex}}\phantom{\rule{0.28em}{0ex}}\ensuremath{\mu}\mathrm{m}$ wide and narrower devices, indicating that the size of the reversed magnetic domain is comparable to the active area of the Hall devices. By counting the number of discrete features, the average diameter of the reversed magnetic domain is estimated to be 80 nm. Individually, the diameter of the reversed domain nucleus is evaluated to be roughly 2 nm. Considering the difference in the diameters of the reversed magnetic domain and the reversed domain nucleus, we ascribed the large coercivity of the ${\mathrm{Co}}_{3}{\mathrm{Sn}}_{2}{\mathrm{S}}_{2}$ thin films to a large nucleation field owing to the uniform crystallinity within grains and strong domain-wall pinning at grain boundaries specific to the thin films. With the large nucleation field in the films, an engineering of the domain-wall pinning sites is a promising approach to control the nucleation, manipulation, and detection of the single domain wall in ${\mathrm{Co}}_{3}{\mathrm{Sn}}_{2}{\mathrm{S}}_{2}$ thin-film devices.

An exploratory study on the impact of COVID-19 on U.S. State boards of accountancy

In the United States (U.S.) individual state boards of accountancy govern the accounting profession within each state. When COVID-19 struck the U.S., state boards worked to maintain normal operations. This study examines how COVID-19 affected the regulatory and oversight activities of the state boards of accountancy and the ways in which boards adapted to the pandemic. We interview executive directors from 21 state boards to determine the pandemic’s impact on board operations and continuing professional education requirements. We also evaluate whether state boards implemented guidance from parties such as the National Association of State Boards of Accountancy (NASBA), and the resources boards had available to navigate the pandemic. Finally, we examine our analyses and findings through the lens of institutional theory. In doing so, we describe how state boards’ individual reactions to the pandemic resulted in a largely homogenous response, as affected by coercive, mimetic, and normative isomorphic mechanisms.

Evolution of Nd-rich phase distribution in Hot-Deformed Nd-Fe-B magnets with different height reductions

In this study, the Nd-rich phases evolution of hot-deformed (HDed) Nd-Fe-B magnets with different height reductions was systematically studied. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results showed that, disorderly oriented platelet-like grains were generated in the hot-pressed magnets subjected to a high-temperature treatment without any deformation. In this case, the grain boundaries (GBs) and triple junction regions (TJRs) provided abundant space for storing Nd-rich phases inside the ribbons. With the height reduction, the platelet-like grains continuously grew and were regularly arranged, resulting in a decrease in GBs and TJRs inside the ribbons. owing to the lack of storage sites, liquid Nd-rich phases can be easily squeezed into the gaps between the ribbons to form blocky Nd-rich phases under pressure. The energy-dispersive X-ray spectroscopy (STEM-EDS) results indicated that the formation of blocky Nd-rich phases not only led to formation of the thin grain boundaries but also resulted in a decrease in the non-ferromagnetic phase element content inside the ribbons. owing to the weakened pinning effect of the GBs on the domain walls, the mechanism of coercivity gradually changed from pinning field control to magnetic domain reversion nucleation. Consequently, with the height decreased by 70%, the remanence increased from 8.32 kGs to 13.62 kGs, while the coercivity significantly decreased from 19.62 kOe to 11.57 kOe. Therefore, it is crucial to avoid the formation of blocky Nd-rich phases for fabricating HDed Nd-Fe-B magnets with high coercivity.

The role of social entrepreneurship in the formation of the social state

The purpose of the scientific article is to analyze the essence of social entrepreneurship and its role in building a social state.
 The results of the study refute the thesis that any state is socially in its essence. Although social policy can be implemented by different methods, and the existence of different models of the social state is a recognized fact, however, different methods and ways may form the essence of the state, which generally corresponds to its social direction.
 The conducted research allows to state the multidimensional role of social entrepreneurship: 1) as a tool for increasing entrepreneurial activity; 2) as an institution of civil society and a means of self-organization of individuals to solve pressing social problems; 3) as a basis for building a social state.Attention is focused on the fact that the institution of social entrepreneurship can be recognized as intersectoral and located on the border of economic, social and legal systems. As an institution of the economic system, social entrepreneurship is a type of entrepreneurship as such, contributes to increasing economic potential and implementing entrepreneurial initiative. As an institution of the social system, social entrepreneurship is aimed at self-organizing individuals to jointly solve the problems of a particular community, since on the ground the problems and needs of the community are much more obvious. At the same time, in the legal system, social entrepreneurship can be considered: 1) in the aspect of civil society, as one of themany means for building a social state governed by the rule of Law; 2) as a component of the subject of legal regulation in economic law.
 It is noted that now the legislation of Ukraine does not provide a legal definition of Social Entrepreneurship, its features are not highlighted and the procedure for carrying out such activities is not regulated. Regulation of social entrepreneurship is carried out within the framework of general regulation of entrepreneurial activity, which does not contribute to its effectiveness, since its purpose and the procedure for using income differ significantly.
 It is concluded that in order to activate social entrepreneurship in wartime and during the country’s recovery from military aggression, the state needs to minimize the use of coercive mechanisms in the economic sphere, expanding the use of legal incentives as much as possible.

Extraction of phase information approximating the demagnetization field within a thin-foiled magnet using electron holography observation.

This paper proposes a method that provides a phase image related to the demagnetization field (Hd) within a thin-foil permanent magnet using electron holography. The observation of Hd remains a significant challenge because electron holography in principle allows only imaging of the magnetic flux density (B), which is a mixture of the contributions from magnetization (M), stray magnetic field (Hs) outside of the specimen and Hd inside of the specimen. The phase map approximating Hd, which was determined by processing of the electron holography observation from a Nd2Fe14B single-crystalline specimen, showed a good agreement with the prediction by micromagnetic theory. With respect to permanent magnets, this method can be applied to examinations about the coercivity mechanism, which is sensitive to the demagnetization field. Graphical Abstract.

Modification on grain boundary phase distribution in PrNd-Cu alloy diffused hot-deformed Nd-Fe-B magnets

Grain boundary diffusion using PrNd-Cu alloy followed pressure induction were applied to optimize the preferential distribution of the diffused eutectic phases in hot-deformed Nd-Fe-B magnets. A value of high coercivity 2.5 T was achieved while the coercivity of the sample with grain boundary modification was then decreased, and the remanence was significantly increased due to the improved grain orientation and reduced volume fraction of the nonferromagnetic phase. Magnetic domain structures of samples were observed and magnetic isolation by diffused nonmagnetic phases was also obtained. The corresponding magnetic domain structure analysis indicated that coercivity was close correlated with the magnetic isolation of grains by the diffused phases. The coercivity mechanisms of the samples were assumed to be domain wall pinning model by the fitted linear relationship of Hcj1/2 versus T2/3 and the initial magnetization curve. The Lorentz TEM investigation confirmed the domain wall pinning at grain boundaries parallel to c-axis.

Feature extended energy landscape model for interpreting coercivity mechanism

Coercivity is expressed as a complex correlation between magnetisation and microstructures. However, owing to multiple intrinsic origins, coercivity has not been fully understood in the framework of the conventional Ginzburg–Landau theory. Here, we use machine learning to draw a realistic energy landscape of magnetisation reversal to consider missing parameters in the Ginzburg–Landau theory. The energy landscape in the magnetisation reversal process is visualised as a function of features extracted via machine learning; the correlation between the reduced feature space and hysteresis loop is assigned. Features in the lower dimension dataset strongly correlate with magnetisation and are embedded with morphological information. We analyse the energy landscape for simulated and experimental magnetic domain structures; a similar trend is observed. The landscape map enables visualisation of the energy of the system and coercivity as a function of feature space components.

Magnetic performance and microstructure of NdFeB sintered magnet by diffusing Tb10Pr90-x(Cu,Al,Ga)x alloys

Commercial NdFeB sintered magnets were processed by grain boundary diffusion process with serial Tb10Pr90-x(Cu,Al,Ga)x (at%) alloys, in order to study the influence of rare earths and non-rare earth metallic elements proportion change on the diffusion effect for alloy diffusion sources with low Tb content. The coercivity increased significantly from 14.20 kOe to 24.10 kOe, 25.46 kOe and 25.36 kOe respectively for the diffused magnets treated with Tb10Pr80(Cu,Al,Ga)10, Tb10Pr60(Cu,Al,Ga)30 and Tb10Pr40(Cu,Al,Ga)50. However, the coercivity optimization effect deteriorated drastically when the total amounts of metallic elements (Cu, Al and Ga) in diffusion resources reached 70 at%. Microstructure analyses demonstrated that the remarkable coercivity enhancements achieved by the relatively low metallic content sources were mainly attributed to the excellent diffusion effects, in which the Tb diffusion depths were rather deeper and the core-shell structures were easily distinguishable. Meanwhile, due to certain differences in thermodynamic characteristics and diffusion behaviors for these serial of diffusion sources, the effective introductions of Tb and Pr from the original coated sources to the inner of the magnets were respectively different. Especially, the utilization rate of Tb obtained an optimum value of 94.74% using Tb10Pr60(Cu,Al,Ga)30 alloy and the utilization rate of Pr reached the peak value of 81.76% in the use of Tb10Pr40(Cu,Al,Ga)50 alloy, providing experiment support for the further design of alloy diffusion sources with low Tb content. In addition, in-situ magnetic domain observation for the typical diffused magnets in this work was carried out to study the demagnetization behavior and coercivity mechanism of the magnet.

A Review of Permanent Magnet Models Used for Designing Electrical Machines

This article serves as an overview of existing models of permanent magnets (PMs) for electrical machines. The review study starts with the linear recoil model, which is commonly used to describe the reversible part of the demagnetizing curve. It is a simple model, especially useful for representing materials with high anisotropy, such as ferrite, NdFeB, and SmCo. The model is harder to apply for nonlinear materials, such as Alnico, but still possible since their recoil curves are linear. The study shows how the linear recoil model could be extended to include irreversible demagnetization, temperature dependence, and angular dependence. All such models have their advantages and disadvantages, which will be discussed further. Both the magnetization and the risk of demagnetization are temperature-dependent. It could be noted that NdFeB has an increased risk of demagnetization at high temperatures, while ferrite has it at very low temperatures. The temperature dependence is described and compared for several materials, also including simplifying models. There are different methods to include the inclination angle of an applied magnetic field when studying the demagnetization of PMs. Several models describe different phenomena associated with the underlying dynamics of magnetism. Such models could then consider coercivity mechanisms and coherent rotation of magnetization, both with the Stoner–Wohlfarth model and models of domain wall motions.

National de‐delegation in multi‐level settings: Independent regulatory agencies in Europe

AbstractNational politicians in Europe have created independent regulatory agencies (IRAs) with significant powers over markets such as communications and energy. After delegation, they have engaged in institutional politicization of IRAs and undertaken numerous attempted or actual de‐delegations. Yet overall de‐delegation over the period 2000–2020 has been limited, as many de‐delegations have been abandoned, temporary or reversed, and also counterbalanced by extensions of IRA powers. The article examines different explanations for this pattern. It looks especially at Europeanization, which has operated through normative and particularly coercive mechanisms. EU coercion has involved threats of legal action, monitoring and enforcement of existing EU legal requirements, and EU legislation expanding IRA powers and protection. IRAs are more vulnerable to de‐delegation than trustee non‐majoritarian institutions because their position can be altered with simple legislative majorities. Yet even for such agents, the ability of national politicians to reverse delegation is constrained by multi‐level institutional settings.

CHINA: THE STORY OF A MISSED OPPORTUNITY. HOW CHINA MANAGED TO DISREGARD THE SOUTH CHINA SEA RULING

On July 12, 2016 an international tribunal (registered with The Hague Permanent Court of Arbitration) ruled against China`s territorial claims in the South China Sea, arguing that the Chinese historic rights within the Nine Dash-Line map have no valid effect under the United Nations Convention on the Law of the Sea (UNCLOS). The tribunal’s decision came at a time when tensions in the South China Sea had reached a very high level amid increasing maritime incidents caused by China and the Chinese government’s construction of artificial islands in the open sea. What was supposed to be a major victory against China for the US-backed states (Vietnam, Philippines), turned out to be only a symbolic success for the Philippines. China not only rejected the sentence, but continued to conduct provocative naval exercises, harass other foreign ships and build artificial islands for military purposes. Using historical research and comparative analysis, this paper illustrates how China’s rejection of the ruling was facilitated by a number of legal, economic and political factors that have diminished international reactions and pressures on the Chinese government: the non-ratification of UNCLOS by the US, the lack of coercive mechanisms to enforce international rulings, the economic interdependence between China and other regional states and the precedents set by other major powers. Keywords: South China Sea, Permanent Court of Arbitration, UNCLOS, maritime claims, historic rights.

"To become like a particle of dust": Dignity as a Gandhian Practice

Most approaches to dignity's history, and its meanings, rely on a hierarchical grammar that elevates the dignified individual. Hierarchy links dignity, through the armament of rights, to coercive bodies and mechanisms that give political substance to dignity claims. This essay seeks in Mohandas Gandhi's thought an alternative practice of dignity, one that departs from this dominant tendency. Unlike most counterparts in the western canon, Gandhian dignity gives ontological priority to vulnerability. Gandhi's anti-hierarchical conception frames dignity in direct relation to existing inequalities, and is elaborated through experiments in proximate living, and via service to the most vulnerable.

Micromagnetic study of magnetization reversal in inhomogeneous permanent magnets

Macroscopic magnetic properties of magnets strongly depend on the magnetization process and the microstructure of the magnets. Complex materials such as hard-soft exchange-coupled magnets or just real technical materials with impurities and inhomogeneities exhibit complex magnetization behavior. Here we investigate the effects of size, volume fraction, and surroundings of inhomogeneities on the magnetic properties of an inhomogeneous magnetic material via micromagnetic simulations. The underlying magnetization reversal and coercivity mechanisms are revealed. Three different demagnetization characteristics corresponding to the exchange coupling phase, semi-coupled phase, and decoupled phase are found, depending on the size of inhomogeneities. In addition, the increase in the size of inhomogeneities leads to a transition of the coercivity mechanism from nucleation to pinning. This work could be useful for optimizing the magnetic properties of both exchange-coupled nanomagnets and inhomogeneous single-phase magnets.

Quantitative analyses of surface and bulk magnetization in Nd2Fe14B and SmCo5 single crystals: towards understanding the large N eff in nucleation-type magnets

The performance of sintered permanent magnets with nucleation-type coercivity mechanism is largely governed by the magnetic state of thin surface layers of constituent grains, and a deeper insight into magnetization–demagnetization processes occurring in the shell part of the grains is very important for further improvement of hard magnetic materials. In this work, we used Nd2Fe14B and SmCo5 single crystals as model objects. By applying magneto-optical Kerr microscopy and conventional magnetometry, we compare the magnetization–demagnetization processes occurring in the thin surface layer and in the volume of both single crystals. We show that upon magnetization along the c-axis, the volume of the single crystals saturates in the field, rigorously determined by demagnetization factor of the bulk sample, whereas in the surface layer a magnetic domain structure exists up to 1.88 T in Nd2Fe14B and 1.19 T in SmCo5 regardless of their bulk demagnetization factors. This means that the surface layer with orientation perpendicular to c-axis magnetizes as a thin magnetic film and has an effective demagnetization factor N eff ∼ 1. We also show that this effect can be reproduced in the framework of conventional finite element method modeling but the analytical solution of this problem still needs to be found. We believe that our findings can be useful for understanding of the formation of a high coercive state in nucleation-type permanent magnets, where the phenomenological concept of the large effective demagnetization factor N eff plays an important role.

Dy evolution and coercivity improvement mechanism of sintered NdFeB magnets in thermal diffusion process

Heavy rare earth (such as Dy) thermal diffusion process is a promising method to increase the coercivity of sintered NdFeB magnets and optimizes their thermal performance. However, the Dy evolution process and the mechanism of coercivity improvement still require further clarification. In this work, commercial 30 M magnets were employed as the initial magnet, and a homemade DyF3 coating was prepared for thermal diffusion treatment. The optimal Dy diffusion process was obtained at 900 ℃ for 8 h. The coercivity of the magnet was increased from 14.16 kOe to 20.43 kOe with a negligible decrease in remanence. The Dy evolution process was systematically analyzed for understanding the mechanism of coercivity improvement. The diffusion coefficient was calculated based on Fick's second law. The diffusivity of Dy along the grain boundaries (5.16 × 10−8 cm2·s−1) is much higher than that in the grains (2.33 × 10−11 cm2·s−1). Therefore, the Dy diffused into the magnet along the grain boundaries with a faster diffusivity, forming uniform and continuous grain boundaries of the Dy-rich phases around the grains, which plays a decoupling effect and significantly increases the coercivity of the magnet. Simultaneously, the Dy in the grain boundaries diffused into the main phase with a slower diffusivity to form a (Nd, Dy)2Fe14B thin layer with higher magnetocrystalline anisotropic, which can inhibit the nucleation of reversed magnetic domains and further improve intrinsic coercivity. However, over diffusion process led to the excess Dy diffused into the grain, which will decrease the performance of the magnet. This work provides an insight of Dy evolution process during the diffusing period, and is significant to understand the improvement mechanism of coercivity for preparing NdFeB magnets with high-performance and low cost.

Engineering microstructure to improve coercivity of bulk MnBi magnet

MnBi is a candidate material for high-temperature magnets because of its increasing coercivity with increasing temperatures up to 255 °C. However, most efforts in fabricating bulk MnBi magnets have run into the problem of preserving the coercivity (Hcj) of its feedstock powders. About 70% of powder's Hcj would be lost during the densification process. Our micromagnetic modeling shows that the coercivity mechanism of the MnBi bulk magnet is controlled by nucleation of the reversal magnetization domains, and the large Hcj loss that occurred during the powder consolidation process can be attributed to the inter-grain magnetic coupling. To attain a high Hcj, the grains in the MnBi bulk magnet must be separated with a non-magnetic grain boundary phase (GBP). To validate this GBP hypothesis, we engineered MnBi bulk magnets with two different types of GBP. The first type of GBP was created in-situ by precipitating excessive Bi from the grains; the second type was created ex-situ by coating silicates on the feedstock powders before the consolidation. While both GBP work, the ex-situ approach resulted in a better Hcj due to a more uniform GBP distribution. The Hcj loss was reduced from 70% to 15%, and the (BH)max of a warm sintered bulk magnet reached 8.9 MGOe.