Magnetic bearing stiffness control using frequency band filtering

Active magnetic bearings can be implemented with frequency band-reject filtering that decreases the bearing stiffness and damping at a small bandwidth around a chosen frequency. The control scheme was used for reducing a rotor dynamic force, such as an imbalance force, transmitted to the bearing stator. The scheme creates additional system vibration modes at the same frequency. It also shows that the amount of force reduction is limited by the stability requirement of these modes

A conventional point of view on active magnetic bearings

Active magnetic bearings used in rotating machinery should be designed as locally controlled, independent devices similar to other types of bearings. The functions of control electronics and power amplifiers can be simply and explicitly related to general bearing properties such as load capacity, stiffness, and damping. The dynamics of a rotor and its supporting active magnetic bearings are analyzed in a modified conventional method with an extended state vector containing the bearing state variables

Global bifurcation for monotone fronts of elliptic equations

In this paper, we present two results on global continuation of monotone front-type solutions to elliptic PDEs posed on infinite cylinders. This is done under quite general assumptions, and in particular applies even to fully nonlinear equations as well as quasilinear problems with transmission boundary conditions. Our approach is rooted in the analytic global bifurcation theory of Dancer and Buffoni--Toland, but extending it to unbounded domains requires contending with new potential limiting behavior relating to loss of compactness. We obtain an exhaustive set of alternatives for the global behavior of the solution curve that is sharp, with each possibility having a direct analogue in the bifurcation theory of second-order ODEs. As a major application of the general theory, we construct global families of internal hydrodynamic bores. These are traveling front solutions of the full two-phase Euler equation in two dimensions. The fluids are confined to a channel that is bounded above and below by rigid walls, with incompressible and irrotational flow in each layer. Small-amplitude fronts for this system have been obtained by several authors. We give the first large-amplitude result in the form of continuous curves of elevation and depression bores. Following the elevation curve to its extreme, we find waves whose interfaces either overturn (develop a vertical tangent) or become exceptionally singular in that the flow in both layers degenerates at a single point on the boundary. For the curve of depression waves, we prove that either the interface overturns or it comes into contact with the upper wall.Comment: 60 pages, 6 figure

Where You Stand Depends on Where You Sit: Bureaucratic Politics in Federal Workplace Agencies Serving Undocumented Workers

This Article integrates social science theory about immigrant incorporation and administrative agencies with empirical data about immigrant-serving federal workplace agencies to illuminate the role of bureaucracies in the construction of rights. More specifically, it contends that immigrants\u27 rights can be protected when workplace agencies incorporate immigrants into labor law enforcement in accordance with the agencies\u27 professional ethos and organizational mandates. Building on Miles\u27 Law that where you stand depends on where you sit, this Article argues that agencies exercise discretion in the face of contested law and in contravention to a political climate hostile to undocumented immigrants for the purpose of protecting workers. Consequently, strongly pro-immigrant policies in the political branches are not necessary for the recovery of immigrants\u27 rights. Instead, entrenched institutional commitments to professional ethics and recognition of organizational mandates constrain politics resulting in a hybrid form of bureaucratic politics. Empirical evidence of regulatory responses to immigrant workers after Hoffman Plastic v. NLRB in three federal agencies serve as comparative case studies: the U.S. Department of Labor, the U.S. Equal Employment Opportunity Commission, and the National Labor Relations Board

Citizenship Denied: Implications of the Naturalization Backlog for Noncitizens in the Military

The immigration system is in crisis. Long lines of asylum seekers at the border and immigrants in the interior spend years waiting for their day in immigration court. This is true in the agencies that process applications for immigration benefits from legal immigrants as well. Since 2016, delays in naturalization have increased to historic proportions. The problem is even worse for military naturalizations, where delays are accompanied by denials and overall declines in military naturalizations. It is the latest front in the battle on legal migration and citizenship. These impediments to citizenship demonstrate an extreme form of policies collectively dubbed the “second wall.” These policies are animated by mistrust of foreigners and immigrant restrictionism, bureaucratic bungling and institutional neglect for service members, and overreliance on national security justifications. These changes affront civil and voting rights for immigrants, diminish military enlistment, and under-mine the institutions of citizenship and democracy. This Article documents barriers to citizenship. More specifically, it analyzes the causes and consequences of citizenship denials in general and military naturalization. It offers solutions that bolster immigrants, the military, and the meaning of citizenship

Leveraging Social Science Expertise in Immigration Policymaking

The longstanding uncertainty about how policymakers should grapple with social science demonstrating racism persists in the modern administrative state. This Essay examines the uses and misuses of social science and expertise in immigration policymaking. More specifically, it highlights three immigration policies that dismiss social scientific findings and expertise as part of presidential and agency decision-making: border control, crime control, and extreme vetting of refugees to prevent terrorism. The Essay claims that these rejections of expertise undermine both substantive and procedural protections for immigrants and undermine important functions of the administrative state as a curb on irrationality in policymaking. It concludes by suggesting administrative, political, and judicial mechanisms that would encourage policymakers to leverage expertise and curb irrationality in immigration policymaking

Leveraging Social Science Expertise in Immigration Policymaking

The longstanding uncertainty about how policymakers should grapple with social science demonstrating racism persists in the modern administrative state. This Essay examines the uses and misuses of social science and expertise in immigration policymaking. More specifically, it highlights three immigration policies that dismiss social scientific findings and expertise as part of presidential and agency decision-making: border control, crime control, and extreme vetting of refugees to prevent terrorism. The Essay claims that these rejections of expertise undermine both substantive and procedural protections for immigrants and undermine important functions of the administrative state as a curb on irrationality in policymaking. It concludes by suggesting administrative, political, and judicial mechanisms that would encourage policymakers to leverage expertise and curb irrationality in immigration policymaking