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61.
Planning collision-free trajectories in time-varying environments: a two-level hierarchy 总被引:1,自引:0,他引:1
We propose a two-level hierarchy for planning collision-free trajectories in time varying environments. Global geometric algorithms for trajectory planning are used in conjunction with a local avoidance strategy. Simulations have been developed for a mobile robot in the plane among stationary and moving obstacles. Essentially, the robot has a global geometric planner that provides a coarse global trajectory (the path and velocity along it), which may be locally modified by the low-level local avoidance module if local sensors detect any obstacles in the vicinity of the robot. This hierarchy makes effective use of the complementary aspects of the global trajectory planning approaches and the local obstacle avoidance approaches. 相似文献
62.
Fincham Frank D.; Beach Steven R. H.; Davila Joanne 《Canadian Metallurgical Quarterly》2007,21(3):542
Does forgiveness predict later conflict resolution in married couples? Twelve-month follow-up data on conflict resolution were collected from the couples studied by F. D. Fincham, S. R. Beach, and J. Davila (see record 2004-11293-007), who had provided earlier reports of forgiveness and conflict resolution. For wives, the positive dimension of forgiveness or benevolence predicted husbands' later reports of better conflict resolution controlling for initial levels of conflict resolution. This finding was independent of wives' marital satisfaction and the degree of hurt engendered by husbands' transgressions. For husbands, the only predictor of wives' reports of later conflict resolution was initial level of conflict resolution. The findings are discussed in terms of the direction of effect between forgiveness and conflict resolution and of the mechanisms that might link them. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
63.
Bellovin Steven M. Benzel Terry V. Blakley Bob Denning Dorothy E. Diffie Whitfield Epstein Jeremy Verissimo Paulo 《Security & Privacy, IEEE》2008,6(1):16-23
A virtual roundtable (featuring panelists Steven Bellovin, Terry Benzel, Bob Blakely, Dorothy Denning, Whitfield Diffie, Jeremy Epstein, and Paulo Verissimo) discussing the next 15 years in computer security. 相似文献
64.
Frischen Alexandra; Bayliss Andrew P.; Tipper Steven P. 《Canadian Metallurgical Quarterly》2007,133(4):694
During social interactions, people's eyes convey a wealth of information about their direction of attention and their emotional and mental states. This review aims to provide a comprehensive overview of past and current research into the perception of gaze behavior and its effect on the observer. This encompasses the perception of gaze direction and its influence on perception of the other person, as well as gaze-following behavior such as joint attention, in infant, adult, and clinical populations. Particular focus is given to the gaze-cueing paradigm that has been used to investigate the mechanisms of joint attention. The contribution of this paradigm has been significant and will likely continue to advance knowledge across diverse fields within psychology and neuroscience. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
65.
Kaslow Nadine J.; Rubin Nancy J.; Forrest Linda; Elman Nancy S.; Van Horne Barbara A.; Jacobs Sue C.; Huprich Steven K.; Benton Sherry A.; Pantesco Victor F.; Dollinger Stephen J.; Grus Catherine L.; Behnke Stephen H.; Miller David S. Shen; Shealy Craig N.; Mintz Laurie B.; Schwartz-Mette Rebecca; Van Sickle Kristi; Thorn Beverly E. 《Canadian Metallurgical Quarterly》2007,38(5):479
Working collaboratively, psychologist educators and trainers at the doctoral, internship, and postdoctoral levels; credentialers; practitioners; and students offer 8 proposals for psychologists to consider in recognizing, assessing, and intervening with problems of professional competence in students and practicing professionals. In the proposals, the authors address the following topics: definitions and categories; preparing the system; self-assessment; remediation; diversity; communication across various levels of the system; confidentiality; and ethical, regulatory, and legal underpinnings. They also propose future directions for the assessment of problems in professional competence in both students and practicing psychologists. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
66.
Lu Shen Beng Jit Tan William S. Willis Francis S. Galasso Steven L. Suib 《Journal of the American Ceramic Society》1994,77(4):1011-1016
Amorphous boron nitride thin coatings (∼0.2 μm) have been formed on Nicalon and C-Nicaion (pre-carbon-coated Nicalon) yarns via dip coating in boric acid solution followed by heating and nitriding in NH3 gas at 1000°C. X-ray photoelectron spectroscopy (XPS) and Auger electron spec-troscopy (AES) studies have shown the formation of boron nitride. The coating was boron rich and contains oxygen. The N/B and O/B ratios range from 0.6 to 0.8 and from 0.1 to 0.25, respectively. Tensile strength measurements revealed that the BN-coated C-Nicalon yarn maintained ∼85% of its original strength while BN-coated Nicalon lost ∼85% of its original strength. Auger depth profiles showed that there was a consumption of carbon during the heating and nitridation process for both BN-coated Nicalon and C-Nicalon fibers. However, the depletion of carbon in BN-coated Nicalon fibers was much more severe than that in BN-coated C-Nicalon fibers. 相似文献
67.
Steven S Fu Miles McFall Andrew J Saxon Jean C Beckham Timothy P Carmody Dewleen G Baker Anne M Joseph 《Nicotine & tobacco research》2007,9(11):1071-1084
We conducted a systematic review of what is known about the relationship between post-traumatic stress disorder (PTSD) and smoking to guide research on underlying mechanisms and to facilitate the development of evidence-based tobacco treatments for this population of smokers. We searched Medline, PsychINFO, and the Cochrane Central Register of Controlled Trials and identified 45 studies for review that presented primary data on PTSD and smoking. Smoking rates were high among clinical samples with PTSD (40%-86%) as well as nonclinical populations with PTSD (34%-61%). Most studies showed a positive relationship between PTSD and smoking and nicotine dependence, with odds ratios ranging between 2.04 and 4.52. Findings also suggest that PTSD, rather than trauma exposure itself, is more influential for increasing risk of smoking. A small but growing literature has examined psychological factors related to smoking initiation and maintenance and the overlapping neurobiology of PTSD and nicotine dependence. Observational studies indicate that smokers with PTSD have lower quit rates than do smokers without PTSD. Yet a few tobacco cessation treatment trials in smokers with PTSD have achieved quit rates comparable with controlled trials of smokers without mental disorders. In conclusion, the evidence points to a causal relationship between PTSD and smoking that may be bidirectional. Specific PTSD symptoms may contribute to smoking and disrupt cessation attempts. Intervention studies that test behavioral and pharmacological interventions designed specifically for use in patients with PTSD are needed to reduce morbidity and mortality in this population. 相似文献
68.
Steven Blaine 《Materials and Structures》1997,30(6):362-365
High energy mixing of calcium sulfate hemihydrate/water slurries provides a means to accelerate the hydration leading to gypsum formation. Additional benefits associated with high energy mixing include enhanced strength of the resulting gypsum casts. In order to exploit the advantages of high energy mixing, an understanding of the relationship between mixing energy and set acceleration is needed. The present study investigated the relationship between a chemical accelerator and high energy mixing for the purpose of set acceleration. A mathematical model of this relationship allows calculation of the time to achieve 50% hydration given the added specific mixing energy, the percentage of added chemical accelerator by weight of stucco, and the water to stucco ratio for a given slurry. Use of this model along with experimental data allowed a comparison of the accelerative efficacy of mixing energy relative to chemical accelerator. The results show that the accelerative capacity of high energy mixing is rather modest compared to that of the chemical accelerator, with a ten-fold increase in mixing energy required to maintain the same time to achieve 50% hydration when the chemical accelerator loading is reduced by 0.03%. 相似文献
69.
70.
Irene B. Zabala-Díaz Vesela I. Chalova Steven C. Ricke 《Sensing and Instrumentation for Food Quality and Safety》2007,1(2):55-61
The importance of lysine determination in feed materials is crucial for the feed industry because this amino acid can be limiting
in many of the cereal materials used for animal feeds. The bacterial gene induction-based assay developed in this study aimed
to measure lysine bioavailability in feeds as an alternative analytical method for animal assays. The advantages of a gene
induction-based approach include rapid and quantitative estimation of many samples and results that relate a bacterial response
to a biological response observed in animals. A whole-cell biosensor strain was constructed using a fluorescent E. coli strain that has an inducible fluorescent phenotype sensitive to extracellular lysine contents. A genetic fusion that links
the promoter of cad operon with a green fluorescent protein encoding gene (gfp) was constructed, and a fluorescent assay was developed. A standard lysine curve (R2 = 0.95) was generated and used for lysine bioavailability quantification of four feed ingredients (whole egg protein, blood-,
soybean-, and meat and bone meal). Quantities as low as 50 μg/ml protein of digested samples were sufficient for analyses
using the biosensor, except for meat and bone meal. Because of the low levels of free lysine in non-digested samples, fluorescence
of these protein sources containing lower than 500 μg/ml protein was not detected (except for soybean meal). The results using
enzymatically digested protein sources showed that the test strain emitted a fluorescent response that was proportional to
the level of lysine present in the feed samples. 相似文献