Manufactured housing comes of age: a support network for resident-owned communities

Owners of manufactured homes who cooperatively purchase the park where they live are discovering benefits such as increased value of homes, decreased maintenance costs, faster resale, and willing lenders.Housing - New Hampshire ; Housing - New England

A computational bow-spring model

Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, February 2011."May 2010." Cataloged from PDF version of thesis.Bow-springs find few applications in industry. Principally, they are used in archery. In addition, they have found some use in a compression-spring mode in the field of biomechatronics, to emulate elastic human legs. The mechanical behavior (characterized by deflected shape and deformation force) is difficult to model, because internal forces and moments and the geometry are both unknown. The only closed-form solutions to such systems are relatively useless to a mechanical engineer. This work comprises an iterative model developed in MATLAB that computes the mechanical behavior of buckled beam (or bow-spring) sections, over a range of parameters and geometries, to be used in the development and testing of compression bow-springs as parallel loading systems to the human leg.by Blake A. Sessions.S.B

A FIELD-PROGRAMMABLE GATE ARRAY IMPLEMENTATION OF A COGNITIVE RADAR TARGET RECOGNITION SYSTEM

The objective of this study is to design a field-programmable gate array (FPGA) implementation of a cognitive radar (CRr) target recognition system for electronic warfare applications. This thesis expands on the closed-loop adaptive matched waveform transmission technique called probability of weighted energy (PWE). This work also investigates the feasibility of applying the PWE technique in a functional digital hardware realization. Initially, a PWE Monte Carlo simulation model is developed in the Verilog hardware description language that is simulated in the Xilinx Vivado environment. The Verilog module components developed in the Monte Carlo model are then incorporated into a CRr target recognition system experiment utilizing the Xilinx VCU118 Evaluation Board. The VCU118 features the Virtex UltraScale+ high-performance FPGA to accomplish CRr adaptive waveform generation and transmission, digital signal processing requirements, and target classification. The Rohde & Schwarz SMW200A Vector Signal Generator and FSW Signal & Spectrum Analyzer function as the radar system transmitter and receiver, respectively, while the FPGA implementation enables the closed feedback loop used by the CRr.Lieutenant Commander, United States NavyApproved for public release; distribution is unlimited

Ytterbium-doped tantalum pentoxide waveguides: spectroscopy for compact waveguide lasers

Ytterbium-doped materials are common gain media in high-performance laser systems. In this work, the first spectroscopic investigation of ytterbium-doped tantalum pentoxide (Yb:Ta2O5) for compact waveguide laser applications is presented

Distributions and abundances of Pacific sardine (Sardinops sagax) and other pelagic fishes in the California Current Ecosystem during spring 2006, 2008, and 2010, estimated from acoustic–trawl surveys

The abundances and distributions of coastal pelagic fish species in the California Current Ecosystem from San Diego to southern Vancouver Island, were estimated from combined acoustic and trawl surveys conducted in the spring of 2006, 2008, and 2010. Pacific sardine (Sardinops sagax), jack mackerel (Trachurus symmetricus), and Pacific mackerel (Scomber japonicus) were the dominant coastal pelagic fish species, in that order. Northern anchovy (Engraulis mordax) and Pacific herring (Clupea pallasii) were sampled only sporadically and therefore estimates for these species were unreliable. The estimates of sardine biomass compared well with those of the annual assessments and confirmed a declining trajectory of the “northern stock” since 2006. During the sampling period, the biomass of jack mackerel was stable or increasing, and that of Pacific mackerel was low and variable. The uncertainties in these estimates are mostly the result of spatial patchiness which increased from sardine to mackerels to anchovy and herring. Future surveys of coastal pelagic fish species in the California Current Ecosystem should benefit from adaptive sampling based on modeled habitat; increased echosounder and trawl sampling, particularly for the most patchy and nearshore species; and directed-trawl sampling for improved species identification and estimations of their acoustic target stre

What Explains the Incidence of the Use of a Common Sediment Control on Lots with Houses Under Construction?

To analyze compliance with one aspect of the regulation of stormwater discharge, we estimate a random-utility model of the probability that a builder uses a silt fence to control sediments on a lot with a house under construction in an urbanizing county of South Carolina. The probability increases if the builder is responsible to the subdivision’s developer or if a homeowners association exists. The probability also increases as the cost to install a silt fence decreases or the number of houses under construction per built house in a subdivision increases. The results can help county officials target inspection to improve compliance.compliance with regulation, erosion and sediment control, filter fabric, management of stormwater runoff, random-utility model, silt fence, storm water pollution prevention plan, Agribusiness, Community/Rural/Urban Development, Demand and Price Analysis, Environmental Economics and Policy, Industrial Organization, Land Economics/Use, Q01, Q24, Q53, Q58,

Sulfur isotope analysis of cysteine and methionine via preparatory liquid chromatography and elemental analyzer isotope ratio mass spectrometry

Rationale: Sulfur isotope analysis of organic sulfur‐containing molecules has previously been hindered by challenging preparatory chemistry and analytical requirements for large sample sizes. The natural‐abundance sulfur isotopic compositions of the sulfur‐containing amino acids, cysteine and methionine, have therefore not yet been investigated despite potential utility in biomedicine, ecology, oceanography, biogeochemistry, and other fields. Methods: Cysteine and methionine were subjected to hot acid hydrolysis followed by quantitative oxidation in performic acid to yield cysteic acid and methionine sulfone. These stable, oxidized products were then separated by reversed‐phase high‐performance liquid chromatography (HPLC) and verified via offline liquid chromatography/mass spectrometry (LC/MS). The sulfur isotope ratios (δ³⁴S values) of purified analytes were then measured via combustion elemental analyzer coupled to isotope ratio mass spectrometry (EA/IRMS). The EA was equipped with a temperature‐ramped chromatographic column and programmable helium carrier flow rates. Results: On‐column focusing of SO2 in the EA/IRMS system, combined with reduced He carrier flow during elution, greatly improved sensitivity, allowing precise (0.1–0.3‰ 1 s.d.) δ³⁴S measurements of 1 to 10 μg sulfur. We validated that our method for purification of cysteine and methionine was negligibly fractionating using amino acid and protein standards. Proof‐of‐concept measurements of fish muscle tissue and bacteria demonstrated differences up to 4‰ between the δ³⁴S values of cysteine and methionine that can be connected to biosynthetic pathways. Conclusions: We have developed a sensitive, precise method for measuring the natural‐abundance sulfur isotopic compositions of cysteine and methionine isolated from biological samples. This capability opens up diverse applications of sulfur isotopes in amino acids and proteins, from use as a tracer in organisms and the environment, to fundamental aspects of metabolism and biosynthesis

Measurement of intact methane isotopologues, including ^(13)CH_3D

Methane (CH_4) is both a significant greenhouse gas and resource. Its present and past cycling can be studied through measurements of concentration and/or bulk isotopic ratios (^(13)C/^(12)C, D/H, and ^(14)C/^(12)C). Currently, isotope ratios are measured by mass spectrometric analysis of H_2 and CO_2 produced from CH_4, or by spectroscopy of CH_4. However, the interpretation of bulk isotopic variations of CH_4 are often equivocal, necessitating additional tracers

Microcomputers in Libraries (Book Review)

published or submitted for publicatio