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71.
This paper addresses the non-preemptive single machine scheduling problem to minimize total tardiness. We are interested in
the online version of this problem, where orders arrive at the system at random times. Jobs have to be scheduled without knowledge
of what jobs will come afterwards. The processing times and the due dates become known when the order is placed. The order
release date occurs only at the beginning of periodic intervals. A customized approximate dynamic programming method is introduced
for this problem. The authors also present numerical experiments that assess the reliability of the new approach and show
that it performs better than a myopic policy. 相似文献
72.
T. Warren Liao 《Applied Soft Computing》2010,10(4):1188-1199
This paper presents two hybrid differential evolution algorithms for optimizing engineering design problems. One hybrid algorithm enhances a basic differential evolution algorithm with a local search operator, i.e., random walk with direction exploitation, to strengthen the exploitation ability, while the other adding a second metaheuristic, i.e., harmony search, to cooperate with the differential evolution algorithm so as to produce the desirable synergetic effect. For comparison, the differential evolution algorithm that the two hybrids are based on is also implemented. All algorithms incorporate a generalized method to handle discrete variables and Deb's parameterless penalty method for handling constraints. Fourteen engineering design problems selected from different engineering fields are used for testing. The test results show that: (i) both hybrid algorithms overall outperform the differential evolution algorithms; (ii) among the two hybrid algorithms, the cooperative hybrid overall outperforms the other hybrid with local search; and (iii) the performance of proposed hybrid algorithms can be further improved with some effort of tuning the relevant parameters. 相似文献
73.
Matt Jones Steve Jones Gareth Bradley Nigel Warren David Bainbridge Geoff Holmes 《Personal and Ubiquitous Computing》2008,12(7):513-525
Listening to music on personal, digital devices whilst mobile is an enjoyable, everyday activity. We explore a scheme for
exploiting this practice to immerse listeners in navigation cues. Our prototype, ONTRACK, continuously adapts audio, modifying
the spatial balance and volume to lead listeners to their target destination. First we report on an initial lab-based evaluation
that demonstrated the approach’s efficacy: users were able to complete tasks within a reasonable time and their subjective
feedback was positive. Encouraged by these results we constructed a handheld prototype. Here, we discuss this implementation
and the results of field-trials. These indicate that even with a low-fidelity realisation of the concept, users can quite
effectively navigate complicated routes.
相似文献
Matt Jones (Corresponding author)Email: |
Steve JonesEmail: |
Gareth BradleyEmail: |
Nigel WarrenEmail: |
David BainbridgeEmail: |
Geoff HolmesEmail: |
74.
The "Early Intervention Programme" (EIP) in Sydney, Australia, is a home-based service for distressed families with children 0-3 years of age. It is funded as a child abuse prevention unit. The concept is based on the work of Selma Fraiberg (1980), who developed the first infant mental health program in Michigan, USA. The goal of the EIP is to strengthen the relationship between parents and child through developmental guidance, psychotherapy and/or provision of active help. The child is seen as an important partner in the intervention process. 相似文献
75.
This paper describes the implementation and evaluation of a nonsanction seat belt law enforcement program in two experimental communities of contrasting size in a state with a mandatory belt law. The main ingredients of the program were seat belt "salutes," public information and education, and limited use of inexpensive economic incentives. Driver shoulder belt use data collected before, during, and after the experimental programs, compared to similar data collected in a comparison community, showed the approach to be effective. While standard seat belt enforcement activities without incentives have been shown to be effective, many police departments, especially in smaller communities, are reluctant to make wholesale increases in seat belt citations. Although requiring some additional level of manpower and resources, a nonsanction approach to seat belt law enforcement can provide an alternate way of increasing belt use in these communities. 相似文献
76.
Optical constants of ice from the ultraviolet to the microwave 总被引:2,自引:0,他引:2
Warren SG 《Applied optics》1984,23(8):1206
77.
Necrotizing enterocolitis (NEC) usually occurs in low birth weight infants who have had perinatal stress, and the mortality remains significant. There are a few reports of NEC in the postoperative period, especially in young infants. Nine neonates developed NEC following operations and form the basis of this report. The interval between operation and the diagnosis of NEC varied from 3 days to 4 mo. The surgical lesions included one case each of esophageal atresia, tetralogy of Fallot, supralevator rectal atresia with rectourethral fistula, and multiple intestinal atresias. Three babies had gastroschisis and two had "apple peel" intestinal atresia. Only 3 of the 9 survived. The usual clinical findings of NEC, abdominal distention, bile stained gastric residuals and diarrhea (with or without blood), can occur in the postoperative period without NEC and are, therefore, not reliable diagnostic signs. Significant changes in the clinical course of these babies occurred from 7 hr to 5 days before the diagnosis was established. In these patients the roentgen findings that established the diagnosis of NEC included intestinal ileus, pneumatosis intestinalis, and portal vein gas. Pneumatosis intestinalis and portal vein gas were the most reliable diagnostic signs, but appeared relatively late in the course of the disease. In one case pneumatosis was seen only in retrospect. None of the patients had definite pneumoperitoneum. Awareness of NEC as a potential postoperative complication may result in early recognition, treatment and survival. 相似文献
78.
Cynipid gall-wasp communities correlate with oak chemistry 总被引:1,自引:0,他引:1
Host-plant association data, gathered from field surveys conducted throughout Florida and from the literature, were used to identify the specificity of cynipid gall inducers to one or more of six Quercus species that occur at Archbold Biological Station, Lake Placid, Florida, USA, including the red oaks Q. laevis, Q. myrtifolia, and Q. inopina, and the white oaks Q. chapmanii, Q. geminata, and Q. minima. Quercus myrtifolia had the highest cynipid richness and diversity (37 cynipid species, Shannon H = 3.61, Simpson's D = 0.97), followed by Q. chapmanii, Q. laevis, Q. inopina, Q. geminata, and finally Q. minima (10 species, H = 2.30, D = 0.90). All cynipid species showed strong fidelity to a particular host plant or a restricted set of host plants. An ordination of gall-wasp host associations indicated that the cynipid communities of each oak species were distinct and specific to a given oak species. Leaf samples taken from each oak species were analyzed for condensed and hydrolyzable tannins, total phenolics, lignin, cellulose and hemicellulose, nitrogen, and carbon. All of these chemical traits, with the exception of carbon, differed by oak species, and the differences were strongly correlated with the axes of the cynipid--species ordination. These results suggest that gall-wasp occurrence is influenced by oak chemistry and imply that experimental studies of cynipid gall inducers that examine host-plant chemistry and female oviposition choice and larval performance will yield useful insights. 相似文献
79.
We review the literature dealing with retrievals of chlorophyll concentrations in the Great Lakes from satellite observations. Most studies show that the satellite estimates of chlorophyll concentrations are linearly related to the observed concentrations, though they tend to overestimate concentrations at lower values and underestimate them at higher values. Deviations from a consistent, accurate, linear relationship can be attributed to temporal and spatial variations in the inherent optical properties of the color producing agents in the water as well as to varying concentrations of non-algal substances that interfere with the retrievals. We confirmed these results by using a simple optical model to examine the sensitivity of the retrieved chlorophyll values to the concentrations of interfering substances and to differences in model parameters. Because the spatial and temporal optical properties of the Great Lakes are unpredictable, no retrieval method is likely to produce accurate results all the time. The papers we reviewed show that simple band ratio algorithms can provide chlorophyll estimates that are proportional to in situ concentrations. The published literature suggests that the band ratio methods will be of most value in regions where the concentrations of non-algal interfering substances are minimal. Because of these limitations we recommend that future papers presenting chlorophyll analysis based on satellite data provide confirming field observations that include measurements of chlorophyll, suspended particles and dissolved organic carbon. We also recommend that Great Lakes scientists explore novel methods for retrieving chlorophyll concentrations from satellite observations that have proven useful in other optically complex waters. 相似文献
80.
Control of nanosystems with frictional dynamics using feedback control methods is important to a wide range of applications of nanotribology. This paper studies the tracking control problem of an array of nanoparticles moving on a substrate with friction between the substrate and the particles. The focus of this study is on control design and stability analysis. The major challenges in this problem include nonlinearities and uncertainties in the frictional dynamics and limited availability of measurable states in nanosystems. The particle–substrate interaction is considered to be unknown, and the unknown effect of unmodeled particle dynamics on the dynamics of the center of mass of the array is also considered. A nonlinear identifier is first developed to identify these unmodeled dynamics. A feedback controller is then developed based on the identifier to control the center of mass of the particles to track a desired trajectory. Boundedness of the closed-loop states and semiglobal asymptotic stability of the tracking error are proven using Lyapunov theory for the case of linear inter-particle interactions. An example with more general Morse-type inter-particle interactions is included to provide some level of confidence that the results are general but not assuredness that they are. Numerical simulation results are provided to demonstrate the performance of the developed identification and control law. 相似文献