A Spatial Decision Support System Approach to Evaluate the Efficiency of a Meals-on-Wheels Program*

Due to limited resources, publicly funded service programs need to operate efficiently. This paper demonstrates how a Spatial Decision Support System (SDSS) can be used to evaluate and enhance the performance of an existing service delivery program. Elements critical to the efficiency of service programs are enumerated. A meals-on-wheels (MOW) program in Connecticut is used as a case study to demonstrate the utility of the SDSS approach. Practical issues related to data sources and system adoption are discussed.     

Inelastic seismic response of torsionally unbalanced systems designed using elastic dynamic analysis

This paper evaluates the inelastic seismic response of torsionally unbalanced structural systems with strength distributed using elastic response spectrum analysis. The structural model is a single mass torsionally unbalanced system with lateral load resisting elements spanning in two principal directions. The element strength is distributed based on elastic response spectrum analysis and three different approaches to incorporate accidental torsion are considered: (a) without incorporating accidental torsion; (b) by applying static floor torques; (c) by shifting the location of the centre of mass. The seismic input is bidirectionally applied at the base of the model. It is shown that the inelastic responses depend strongly on the torsional stiffness of the system. For a torsionally stiff system, the torsional response leads to a decrease in the stiff edge displacement; however, for a torsionally flexible system, it tends to increase the stiff edge displacement. Using response spectrum analysis without including accidental torsion may lead to excessive additional ductility demand on the stiff edge element. With accidental torsion effect incorporated, the response spectrum analysis will give a strength distribution such that there will be no excessive additional ductility demands on the lateral load resisting elements.     

Three-dimensional response of a cylindrical canyon in a layered half-space

An indirect boundary-method formulation to obtain the three-dimensional response of an infinitely long canyon of uniform but arbitrary cross-section cut in a layered viscoelastic half-space is presented. Seismic excitation in the form of plane elastic waves acting at an arbitrary angle with respect to the axis of the canyon is considered. Numerical results for SH-, SV- and P-wave excitation of a circular canyon and of a canyon with a topography similar to that in the vicinity of Pacoima Dam are discussed in some detail.     

Isolation of soil-structure interaction effects by full-scale forced vibration tests

Forced vibration tests designed to isolate the effects of soil-structure interaction are described and the results obtained for the nine-storey reinforced concrete Millikan Library Building are analysed. It is shown that it is possible to determine experimentally the fixed-base natural frequencies and modal damping ratios of the superstructure. These values may be significantly different from the resonant frequencies and damping ratios of the complete structure-foundation-soil system. It is also shown that forced vibration tests can be used to obtain estimates of the foundation impedance functions. In the case of the Millikan Library it is found that during forced vibration tests the rigid-body motion associated with translation and rocking of the base accounts for more than 30 per cent of the total response on the roof and that the deformation of the superstructure at the fundamental frequencies of the system is almost entirely due to the inertial forces generated by translation and rocking of the base.     

Pigment analysis and spectral assessment of spruce trees undergoing forest decline in the NE United States and Germany

Measurement of photosynthetic pigments as ground truth for remotely sensed spectra of boreal communities was tested. Chlorophyll and carotenoid concentrations and ratios were obtained from needles of spruce trees which were healthy as well as those undergoing forest decline (Waldsterben) in Vermont (USA) and Baden-Württemberg (FR Germany). In needles of trees exhibiting forest decline symptoms, chlorophyll pigment concentrations were lower, chlorophyll b levels decreased relative to chlorophyll a, total chlorophyll (a + b) was less relative to total carotenoid, and percent of reflectance in the visible range was higher. Pigment and reflectance data differentiated between needles from healthy and declining sites. These results were compared to remotely sensed spectral data obtained by aircraft and satelitee. As a result of these initial comparisons, it appears that using photosynthetic pigments as ground truth for remotely sensed spectral data may be of value in developing techniques for differentiating undamaged and damaged tree canopies on a large spatial scale. Finally, similar pigment and reflectance properties characterized healthy and declining communities in both Vermont and Baden-Württemberg.     

An experimental marine ecosystem response to crude oil and corexit 9527: Part 1—Fate of chemically dispersed crude oil

The fate of Prudhoe Bay crude oil. labelled with n(1−¹⁴C)-hexadecane and dispersed with Corexit 9527, was studied for 24 days in a polyethylene bag enclosure of sea water by time-series observations of the alkane composition of the crude oil, oil fluorescence, ¹⁴C-labelled hexadecane in the particulate phase, bacterial biomass, amounts of sedimented material and parameters of temperature, salinity, particulate organic carbon and nitrogen, and nutrients. By the seventh day, convective and diffusive mixing, important mechanisms for the dispersion of oil, resulted in a fairly homogeneous distribution of oil throughout the enclosed water column. Rapid bacterial biodegradation removed the n-alkane fraction initially, while oil-Corexit dispersion suppressed phytoplankton growth. After 7 days, with the recovery of phytoplankton growth, much of the aged oil sedimented with sinking of diatoms.     

A simple deep-towed vertical array for high-resolution reflection seismic profiling

A simple, low cost, deep-towed system for high-resolution reflection seismic profiling is described. It consists of a vertical array with two hydrophones having a separation of 2.2 m and rigidly mounted onto streamlined tow bodies. Improvement of the signal-to-noise ratio is attained by simple stacking of the hydrophone outputs after signal conditioning and travel time corrections. The suppression of side echoes and surface reflections is achieved by an analog procedure which in effect improves the directional characteristics of the array. A circuit for automatic gain control is included to enhance weak signals as well as to suppress ringing.Results in Kiel Bay and over the crest of the Jan Mayen Ridge (northern Atlantic) suggest that this simple vertical array may supplement air gun systems better than conventional, surface pinger-type equipment.Institute of Geophysics     

The effect of glucose on the productivity of seawater: An experimental approach using controlled aquatic ecosystems

Small quantities (1 to 5 mg litre) of glucose were added to 60-ton enclosed water columns together with inorganic nutrients. Heterotrophic production by bacteria in the glucose-enriched water columns depressed photosynthetic production by algae. This effect was believed to have been caused by heterotrophic growth out-competing the autotrophic organisms for a limited supply of nitrate. Secondary and tertiary production in the glucose-enriched water columns was higher than under conditions of predominantly autotrophic production.     

Heat flow and quantity of methane deduced from a gas hydrate field in the vicinity of the Dnieper Canyon,northwestern Black Sea

Seismic reflection data document for the first time the existence of a BSR in a limited area west of the Dnieper Canyon in the northwestern Black Sea. Seismic wide-angle data suggest that gas hydrates occupy in average 15±2% of the pore space in a zone of 100 m in thickness. A conservative quantification of the amount of methane associated with this gas hydrate occurrence is about 12±3×10¹¹ m³ (0.6±0.2 Gt of methane carbon). Conductive heat flow deduced from the BSR depth is in the range of 21±6 to 55±15 mW m^–2.     

Crack Coalescence in Molded Gypsum and Carrara Marble: Part 1. Macroscopic Observations and Interpretation

Cracking and coalescence behavior has been studied experimentally with prismatic laboratory-molded gypsum and Carrara marble specimens containing two parallel pre-existing open flaws. This was done at both the macroscopic and the microscopic scales, and the results are presented in two separate papers. This paper (the first of two) summarizes the macroscopic experimental results and investigates the influence of the different flaw geometries and material, on the cracking processes. In the companion paper (also in this issue), most of the macroscopic deformation and cracking processes shown in this present paper will be related to the underlying microscopic changes. In the present study, a high speed video system was used, which allowed us to precisely observe the cracking mechanisms. Nine crack coalescence categories with different crack types and trajectories were identified. The flaw inclination angle (β), the ligament length (L), that is, intact rock length between the flaws, and the bridging angle (α), that is, the inclination of a line linking up the inner flaw tips, between two flaws, had different effects on the coalescence patterns. One of the pronounced differences observed between marble and gypsum during the compression loading test was the development of macroscopic white patches prior to the initiation of macroscopic cracks in marble, but not in gypsum. Comparing the cracking and coalescence behaviors in the two tested materials, tensile cracking generally occurred more often in marble than in gypsum for the same flaw pair geometries.