New Geometric Algorithms for Fully Connected Staged Self-Assembly

We consider staged self-assembly systems, in which square-shaped tiles can be added to bins in several stages. Within these bins, the tiles may connect to each other, depending on the glue types of their edges. Previous work by Demaine et al. showed that a relatively small number of tile types suffices to produce arbitrary shapes in this model. However, these constructions were only based on a spanning tree of the geometric shape, so they did not produce full connectivity of the underlying grid graph in the case of shapes with holes; designing fully connected assemblies with a polylogarithmic number of stages was left as a major open problem. We resolve this challenge by presenting new systems for staged assembly that produce fully connected polyominoes in O(log^2 n) stages, for various scale factors and temperature {\tau} = 2 as well as {\tau} = 1. Our constructions work even for shapes with holes and uses only a constant number of glues and tiles. Moreover, the underlying approach is more geometric in nature, implying that it promised to be more feasible for shapes with compact geometric description.Comment: 21 pages, 14 figures; full version of conference paper in DNA2

Developing the Service Sector as an Engine of Growth for Asia

[Excerpt] This book takes an in-depth look at the barriers that stand in the way of service sector development in Asia to systematically assess the prospects for the sector to be an engine of growth. It covers a number of themes that are relevant for the sector throughout the region including trade, foreign direct investment, the relationship between services and growth, and the emerging information technology–business process outsourcing industry. It also includes studies on the service sectors of five major Asian economies: the People’s Republic of China, India, the Republic of Korea, the Philippines, and Thailand. The book is the key output of an ADB regional technical assistance research project financed by the e-Asia and Knowledge Partnership Fund established by the Republic of Korea at the Asian Development Bank. The project benefited from in-depth collaboration with the Peterson Institute for International Economics, one of the world’s top think tanks

Measurements of Frequency, Temperature, RF Field Dependent Surface Resistance Using Superconducting Half-Wave Cavity

A theory of surface resistance of superconductor was rigorously formulated by Bardeen, Cooper, Schrieffer more than 50 years ago. Since then the accelerator community has been used the theory as a guideline to improve the surface resistance of the superconducting cavity. It has been observed that the surface resistance is dependent on frequency, temperature and rf field strength, and surface preparation. To verify these dependences, a well-controlled study is required. Although many different types of cavities have been tested, the typical superconducting cavities are built for specific frequencies of their application. They do not provide data other than at its own frequency. A superconducting half wave cavity is a cavity that enables us to collect the surface resistance data across frequencies of interest for particle accelerators and evaluate preparation techniques. This paper will present the design of the half wave cavity, its electromagnetic mode characteristics and experimental results

Investigation of the Surface Resistance of Niobium Between 325 MHz and 1300 MHz Using a Coaxial Half-wave Cavity

The Center for Accelerator Science at Old Dominion University has built a half-wave coaxial cavity (*) to measure the surface resistance of niobium as a function of frequency, temperature, rf field, preparation techniques, over a wide range of frequencies of interest for particle accelerators. The characteristics of the half-wave coaxial cavity provide these information on a same surface. The preliminary results showed clearly the frequency dependence of residual surface resistance (**). After establishing baseline, we have conducted a study of low temperature baking effect on the surface resistance under controlled environment. This paper will describe the details of the test procedure, results and we will explore underlying physics of the phenomenon. * H. Park et al., MOPB003, Proc. SRF2015, http://jacow.org/** H. Park et al., THPB080, Proc. SRF2017, http://jacow.org

Measurement of Surface Resistance Properties With Coaxial Resonators - Review

Achieving ever decreasing surface resistance at higher field in superconducting RF accelerating structures is one of most outstanding developments in modern accelerators. The BCS theory has been used widely to estimate the surface resistance and to direct the technology. However, recent research results show that the behavior of the surface resistance further deviates from the BCS theory. So far the study on surface resistance was performed usually with cavities of single frequency which limited the study of frequency dependent surface resistance. The Center for Accelerator Science at Old Dominion University has designed and built several half wave coaxial cavities to study the frequency, temperature, and RF field dependence of surface resistance. TRIUMF in Canada also joined this line of research using such multi frequency quarter wave and half wave coaxial cavities. This type of multi mode cavity will allow us to systematically study the parameters affecting surface resistance on the same cavity surface. In this paper, we review the results ODU and TRIUMF collected so far and proper analysis methods

Fabrication and Testing of a Prototype RF-Dipole Crabbing Cavity

Crabbing cavities are essential in particle colliders to compensate the luminosity degradation due to beam collision at a crossing angle. The 952.6 MHz 2-cell rf-dipole crabbing cavity system was proposed for the Jefferson Lab Electron-Ion Collider to restore the head-on collisions of electron and proton bunches at the interaction point. A prototype cavity was designed and developed to demonstrate the performance of multi-cell rf-dipole structures. This paper presents the fabrication process and cold test results of the first 2-cell rf-dipole prototype cavity

Lessons learned from RF-Dipole Prototype Cavities for LHC High Luminosity Upgrade

The RF-Dipole Crabbing Cavity designed for the LHC High Luminosity Upgrade includes two higher order mode (HOM) couplers. One of the HOM couplers is an rf filter, which is a high pass filter designed to couple to the horizontal dipole modes and accelerating modes up to 2 GHz, while rejecting the fundamental operating mode at 400 MHz. The coupler consists of a high pass filter circuit where the rejection of the operating mode and transmission of HOMs are sensitive to dimensional deviations. An rf test box has been designed to measure the transmission of the rf filter in order to qualify the fabricated HOM coupler and to tune the coupler. This paper presents the measurements of the HOM coupler with the rf test box

Cryogenic Test Results of the SPS Prototype RF-Dipole Crabbing Cavity With Higher Order Mode Couplers

The rf-dipole crabbing cavity planned for the LHC High Luminosity Upgrade is designed to deliver a transverse kick of 3.34 MV; crabbing the proton beam in the horizontal plane. The proton beams of the LHC machine operating at 7 TeV each sets high impedance thresholds on the crabbing cavity systems. The rf-dipole crabbing cavity is designed with a two higher order mode couplers to suppress those HOMs. The first prototype of the HOM couplers are fabricated at Jefferson Lab. This paper reports the cryogenic test results of the HOM couplers with the SPS prototype rf-dipole cavity

Design of a Proof-of-Principle Crabbing Cavity for the Jefferson Lab Electron-Ion Collider

The Jefferson Lab design for an electron-ion collider (JLEIC) requires crabbing of the electron and ion beams in order to achieve the design luminosity. A number of options for the crabbing cavities have been explored, and the one which has been selected for the proof-of-principle is a 952 MHz, 2-cell rf-dipole (RFD) cavity. This paper summarizes the electromagnetic design of the cavity and its HOM characteristics

Universal Small Payload Interface – A Design to Ensure Cost-Effective Small Satellite Access to Space

Launch vehicle economies of scale are one of the biggest hurdles to cheaper space access for small satellites. Overhead and facilities and other costs are constant regardless of the launch vehicle size. Therefore for smaller launch vehicles, cost efficiency drops, increasing the per-kilogram launch vehicle costs. Consequently, the cost advantage of small satellites is rapidly diminished because the overall mission cost remains high. One solution is launching piggyback on a large launch vehicle. Large launch vehicles have opaque procedures and lack clear requirements and standardized piggyback accommodations. The Ariane ASAP 5 provides reliable and easy launch for small satellites, but there is no U.S. counterpart to it. The Universal Small Payload Interface (USPI) project sponsored by the NRO will remedy that situation. The USPI will provide standardized accommodation on large launch vehicles for small payloads. USPI provides a standard requirements document, a detailed integration flow, separation system, and payload platform design for the widest possible flexibility in terms of reliable and cost effective access to space