Debris control design achievements of the booster separation motors

The stringent debris control requirements imposed on the design of the Space Shuttle booster separation motor are described along with the verification program implemented to ensure compliance with debris control objectives. The principal areas emphasized in the design and development of the Booster Separation Motor (BSM) relative to debris control were the propellant formulation and nozzle closures which protect the motors from aerodynamic heating and moisture. A description of the motor design requirements, the propellant formulation and verification program, and the nozzle closures design and verification are presented

Structure of the western Somali Basin

Originally issued as Reference No. 67-38, series later renamed WHOI-. Reprint from Journal of Geophysical Research, vol. 72, no. 10, May 1967.The western Somali Basin in the northwestern Indian Ocean is covered by thick deposits of terrigenous sediments. Seismic reflection profiles show, however, the northern and southern parts to be very different. The northern sections is a deep basin filled with thick uniformly stratified sediments. It is enclosed by the continental margin to the west and north, Chain ridge to the east, and shallow basement structure to the south. A change in depth of basement occurs along an approximately east-west line at latitude 3°30'N very near the southern end of Chain ridge. In the southern portion of the basin the basement is shallow, and, immediately south of latitude 3°30'N, it has high relief. Stratified flat-lying sediments fill the basement depressions, and isolated hills formed of basement material rise above the abyssal plain deposits. Farther to the south the abyssal plain becomes very narrow. Gabbro dredged from the southeast slope of Chain ridge has been dated by the potassium-argon method as 89.6 ± 4.5 m.y., which should be considered a minimum age. The evidence suggests that the entire sediment sequence of the northern basin was deposited subsequent to the formation of the ridge. The thin sediment cover of the southern portion of the basin is probably no older than Tertiary.Office of Naval Research under contract Nonr-4029(00) NR 260-101

Assessing Human Error Against a Benchmark of Perfection

An increasing number of domains are providing us with detailed trace data on human decisions in settings where we can evaluate the quality of these decisions via an algorithm. Motivated by this development, an emerging line of work has begun to consider whether we can characterize and predict the kinds of decisions where people are likely to make errors. To investigate what a general framework for human error prediction might look like, we focus on a model system with a rich history in the behavioral sciences: the decisions made by chess players as they select moves in a game. We carry out our analysis at a large scale, employing datasets with several million recorded games, and using chess tablebases to acquire a form of ground truth for a subset of chess positions that have been completely solved by computers but remain challenging even for the best players in the world. We organize our analysis around three categories of features that we argue are present in most settings where the analysis of human error is applicable: the skill of the decision-maker, the time available to make the decision, and the inherent difficulty of the decision. We identify rich structure in all three of these categories of features, and find strong evidence that in our domain, features describing the inherent difficulty of an instance are significantly more powerful than features based on skill or time.Comment: KDD 2016; 10 page

Studies in the statistical and thermal properties of hadronic matter under some extreme conditions

The thermal and statistical properties of hadronic matter under some extreme conditions are investigated using an exactly solvable canonical ensemble model. A unified model describing both the fragmentation of nuclei and the thermal properties of hadronic matter is developed. Simple expressions are obtained for quantities such as the hadronic equation of state, specific heat, compressibility, entropy, and excitation energy as a function of temperature and density. These expressions encompass the fermionic aspect of nucleons, such as degeneracy pressure and Fermi energy at low temperatures and the ideal gas laws at high temperatures and low density. Expressions are developed which connect these two extremes with behavior that resembles an ideal Bose gas with its associated Bose condensation. In the thermodynamic limit, an infinite cluster exists below a certain critical condition in a manner similar to the sudden appearance of the infinite cluster in percolation theory. The importance of multiplicity fluctuations is discussed and some recent data from the EOS collaboration on critical point behavior of nuclei can be accounted for using simple expressions obtained from the model.Comment: 22 pages, revtex, includes 6 figures, submitted to Phys. Rev.

Classification of the Nuclear Multifragmentation Phase Transition

Using a recently proposed classification scheme for phase transitions in finite systems [Phys.Rev.Lett.{\bf 84},3511 (2000)] we show that within the statistical standard model of nuclear multifragmentation the predicted phase transition is of first order.Comment: 5 pages, 4 eps figures, accepted for publication in Phys.Rev.C (in press

Ab initio equilibrium constants for H2O–H2O and H2O–CO2

Ab initio 6‐31G** electronic structure calculations have been used to determine the minimum energy geometries and vibrational frequencies of molecular clusters of water and carbon dioxide. Application of statistical thermodynamics leads to theoretical equilibrium constants for gas phase dimerization of water and the formation of an adduct of carbon dioxide with water.The low energy vibrations of the clusters lead to much larger contributions to the vibrational partitioning of the energy than do the fundamental vibrations of the monomeric species. A new ‘‘Harmonic‐Morse’’ formula is derived to estimate anharmonicity from optimized harmonic frequencies and two additional values on the potential surface for each vibration. These ab initiocalculations of equilibrium constants are very close to recent measurements and fall within the range of values obtained by other methods. This no‐parameter treatment gives excellent agreement for the equilibrium of H2O–CO2 near the supercritical fluid range of CO2 and suggests that a ‘‘Theory of Significant Clusters’’ may be extended to a model of supercritical fluids which includes the effects of anharmonicity

Molecular Beams

Contains research objectives and reports on two research projects.Joint Services Electronics Programs (U. S. Army, U. S. Navy, and U. S. Air Force) under Contract DA 28-043-AMC-02536(E)Sloan Fund for Basic Research (M. I. T. Grant 249

Expert chess memory: Revisiting the chunking hypothesis

After reviewing the relevant theory on chess expertise, this paper re-examines experimentally the finding of Chase and Simon (1973a) that the differences in ability of chess players at different skill levels to copy and to recall positions are attributable to the experts' storage of thousands of chunks (patterned clusters of pieces) in long-term memory. Despite important differences in the experimental apparatus, the data of the present experiments regarding latencies and chess relations between successively placed pieces are highly correlated with those of Chase and Simon. We conclude that the 2-second inter-chunk interval used to define chunk boundaries is robust, and that chunks have psychological reality. We discuss the possible reasons why Masters in our new study used substantially larger chunks than the Master of the 1973 study, and extend the chunking theory to take account of the evidence for large retrieval structures (templates) in long-term memory

Randomly Broken Nuclei and Disordered Systems

Similarities between models of fragmenting nuclei and disordered systems in condensed matter suggest corresponding methods. Several theoretical models of fragmentation investigated in this fashion show marked differences, indicating possible new methods for distinguishing models using yield data. Applying nuclear methods to disordered systems also yields interesting results.Comment: 10 pages, 4 figure

Mass measurements near the rr-process path using the Canadian Penning Trap mass spectrometer

The masses of 40 neutron-rich nuclides from Z = 51 to 64 were measured at an average precision of $\delta m/m= 10^{-7}$ using the Canadian Penning Trap mass spectrometer at Argonne National Laboratory. The measurements, of fission fragments from a $^{252}$Cf spontaneous fission source in a helium gas catcher, approach the predicted path of the astrophysical $r$ process. Where overlap exists, this data set is largely consistent with previous measurements from Penning traps, storage rings, and reaction energetics, but large systematic deviations are apparent in $\beta$-endpoint measurements. Differences in mass excess from the 2003 Atomic Mass Evaluation of up to 400 keV are seen, as well as systematic disagreement with various mass models.Comment: 15 pages, 16 figures. v2 updated, published in Physical Review