A computer system for hurricane hazard assessment

Rapid economic development and population growth in coastal regions of the U.S. has resulted in an increase in vulnerability of population and property to the hurricane hazard. State and local emergency management officials need a detailed information base of potential loss estimates to prepare sound emergency preparedness plans. A computer system, known as the Vulnerability Assessment and Mapping System (VAMS), has been designed to estimate the extent and spatial distribution of potential casualties, and losses to housing and commercial-industrial facilities as a result of hurricane landfall. The VAMS system is flexible as users can choose to consider different types of hurricanes with varying surge and wind patterns and points of landfall for determining potential loss estimates within a given study area. The results of the analysis can be displayed in computer-generated grid map form or as summary statistics in tabular form.The VAMS system is then applied to coastal portions of the Houston-Galveston metropolitan area in the State of Texas. The VAMS system is part of a comprehensive hurricane impact study for the Texas Governor's Division of Emergency Management.     

Tandem mirror reactor with thermal barriers

A new invention — the thermal barrier — promises to improve the tandem mirror fusion reactor. The thermal barrier consists of a region of reduced magnetic field strength, plasma density, and plasma potential between each end plug and the central cell of a tandem mirror. The depressed plasma potential serves to thermally insulate the plug electrons from the central cell electrons. With barriers and auxiliary electron heating in the plugs, the central cell confining potential can be generated with a lower plug plasma density, magnetic field strength, and beam injection energy than for the case without barriers. This paper summarizes the status of the rapidly evolving physics knowledge concerning tandem mirrors with thermal barriers, describes end plug components typical for tandem mirror reactors — yin-yang magnets, neutral beams, and ECRH heating systems, and discusses central cell design.     

Allelopathic effects ofPolygonum aviculare L.

We previously reported thatPolygonum aviculare has a strong allelopathic action againstCynodon dactylon (L.) Pers. and other test species. Moreover, we found that several phenolic compounds appeared to be important allelochemics in this activity. We have now isolated other potential inhibitors fromP. aviculare residues and soil underPolygonum stands, and none of these occurred in soil underC. dactylon stands. GC-MS analysis revealed that these additional inhibitors are long-chain fatty acids with 14–22 carbons. Nine were identified inP. aviculare residues and seven in soil underP. aviculare. Sodium salts of all the identified fatty acids inhibited seedling growth ofC. dactylon and at least some test strains of the nitrogen-fixing bacteria,Azotobacter andRhizobium.     

Relaxed Balance Using Standard Rotations

Abstract. In search trees with relaxed balance, rebalancing transformations need not be connected with updates, but may be delayed. For standard AVL tree rebalancing, we prove that even though the rebalancing operations are uncoupled from updates, their total number is bounded by O(M log (M+N)) , where M is the number of updates to an AVL tree of initial size N . Hence, relaxed balancing of AVL trees comes at no extra cost asymptotically. Furthermore, our scheme differs from most other relaxed balancing schemes in an important aspect: No rebalancing transformation can be done in the wrong direction, i.e., no performed rotation can make the tree less balanced. Moreover, each performed rotation indeed corresponds to a real imbalance situation in the tree. Finally, and perhaps most importantly, our structure is capable of forgetting registered imbalance if later updates happen to improve the situation. Our results are of theoretical interest and have possible sequential and parallel applications.     

Multidisciplinary in-depth investigations of head-on and left-turn road collisions

To enhance traffic safety, a multidisciplinary Road Accident Investigation Team was established in Denmark for a 2-year trial period. The objective was to conduct in-depth investigations of specific types of accidents, and to identify effective preventive measures. The team consisted of a road engineer, a vehicle inspector, a police superintendent, a psychologist and a physician. Seventeen serious head-on collisions as well as 17 left-turn collisions were analysed. In collecting data, police reports were supplemented by the team's investigation of accident sites and vehicles involved, and interviews were carried out with the involved road users and witnesses. The drivers, to whom the accident factors were primarily related in the head-on collisions, were characterised by their conscious risk-taking behaviour. They were all males; several of them were under age 40 and had earlier traffic and/or drug convictions. The main accident factors were excessive speed, drunk driving and driving under the influence of illegal drugs. In the left-turn accidents, the most common accident factors were attention errors, and it was also noted that elderly drivers ( > 74) were over-represented. The synergy effect of working as a multidisciplinary team proved fruitful. It resulted in a more precise knowledge of the road accident circumstances and of contributing factors leading up to the accidents. Due to the great demand on resources, only a limited number of accidents could be analysed, but the results provide a basis for further and more targeted research.