11,544 research outputs found
Teleprinter uses thermal printing technique
Alphameric/facsimile printer receives serial digital data in the form of a specified number of bits per group and prints it on thermally sensitive paper. A solid state shift-register memorizes the incoming serial digital data
Aerocrane: A hybrid LTA aircraft for aerial crane applications
The Aerocrane, a hybrid aircraft, combines rotor lift with buoyant lift to offer VTOL load capability greatly in excess of helicopter technology while eliminating the airship problem of ballast transfer. In addition, the Aerocrane concept sharply reduces the mooring problem of airships and provides 360 deg vectorable thrust to supply a relatively large force component for control of gust loads. Designed for use in short range, ultra heavy lift missions, the Aerocrane operates in a performance envelope unsuitable for either helicopters or airships. Basic design considerations and potential problem areas of the concept are addressed
Low cost fabrication development for oxide dispersion strengthened alloy vanes
Viable processes were developed for secondary working of oxide dispersion strengthened (ODS) alloys to near-net shapes (NNS) for aircraft turbine vanes. These processes were shown capable of producing required microstructure and properties for vane applications. Material cost savings of 40 to 50% are projected for the NNS process over the current procedures which involve machining from rectangular bar. Additional machining cost savings are projected. Of three secondary working processes evaluated, directional forging and plate bending were determined to be viable NNS processes for ODS vanes. Directional forging was deemed most applicable to high pressure turbine (HPT) vanes with their large thickness variations while plate bending was determined to be most cost effective for low pressure turbine (LPT) vanes because of their limited thickness variations. Since the F101 LPT vane was selected for study in this program, development of plate bending was carried through to establishment of a preliminary process. Preparation of ODS alloy plate for bending was found to be a straight forward process using currently available bar stock, providing that the capability for reheating between roll passes is available. Advanced ODS-NiCrAl and ODS-FeCrAl alloys were utilized on this program. Workability of all alloys was adequate for directional forging and plate bending, but only the ODS-FeCrAl had adequate workability for shaped preform extrustion
Lightweight, self-evacuated insulation panels
Multilayer insulation of prefabricated panels is developed for cryogenic storage tanks. System utilizes panels of aluminized Mylar separated by sheets of low conductivity polyurethane foam. Panels are self-evacuated by cryopumping of gaseous carbon dioxide at time of use
Rigid open-cell polyurethane foam for cryogenic insulation
Lightweight polyurethane foam assembled in panels is effective spacer material for construction of self-evacuating multilayer insulation panels for cryogenic liquid tanks. Spacer material separates radiation shields with barrier that minimizes conductive and convective heat transfer between shields
The role of spatial and temporal radiation deposition in inertial fusion chambers: the case of HiPERÂż
The ïŹrst wall armour for the reactor chamber of HiPER will have to face short energy pulses of 5 to 20 MJ mostly in the form of x-rays and charged particles at a repetition rate of 5â10 Hz. Armour material and chamber dimensions have to be chosen to avoid/minimize damage to the chamber, ensuring the proper functioning of the facility during its planned lifetime. The maximum energy ïŹuence that the armour can withstand without risk of failure, is determined by temporal and spatial deposition of the radiation energy inside the material. In this paper, simulations on the thermal effect of the radiationâarmour interaction are carried out with an increasing deïŹnition of the temporal and spatial deposition of energy to prove their inïŹuence on the ïŹnal results. These calculations will lead us to present the ïŹrst values of the thermo-mechanical behaviour of the tungsten armour designed for the HiPER project under a shock ignition target of 48 MJ. The results will show that only the crossing of the plasticity limit in the ïŹrst few micrometres might be a threat after thousands of shots for the survivability of the armour
Making an impression: error location and repertoire features affect performance quality rating processes
This article examines the effects of composition length, familiarity, and likeabilityâas well as the location of performance errorsâon the process of forming performance quality ratings. Five piano works by Chopin and a twentieth-century composer were cho- sen to vary by length and familiarity. Three of these pieces were then manipulated to contain performance errors in the opening material, and two of those the same error at the recapitulation. Forty-two musicians provided continuous quality evaluations and final quality ratings of the performances, hearing one version of each piece. The results showed that familiarity had no effect within works of a well-known composer, but times to first and final decision were significantly extended for an unfamiliar work of an unfamiliar composer. A shorter piece led to a shorter time to first decision. An error at the beginning of a performance caused a shorter time to first decision and lower initial and final ratings, where the same error at the recapitulation did not have a significant effect on the final judgment, despite causing a temporary negative drop. These findings demonstrate how evaluatorsâ knowledge of a work can affect their rating process and the importance of making a strong first impression in performance
Experienced tutors' deployment of thinking skills and what might be entailed in enhancing such skills
In the context of research that reports weaknesses in adults' critical thinking skills, the primary aim was to examine adults' use of critical thinking skills that are described in taxonomies and to identify areas for development. Position papers written by an opportunity sample of 32 experienced adult educators formed the data for a descriptive sample survey design intended to reveal participants' use of critical thinking skills. Each 6000-word paper was written during a development programme that supported such skills. A content analysis of the papers revealed that when participants drew on personal and published ideas about learning to derive their proposals for change, they accepted the ideas uncritically, thereby implying that they might find it difficult to help learners to examine ideas critically. The evidence supports research that implies that critical thinking skills are unlikely to develop unless overall course design privileges the development of epistemological understanding (King and Kitchener 1994, Kuhn 1999). A fundamental assumption underlying the study is that this understanding influences effective citizenship and personal development, as well as employability. A proposition that merits attention in future research is that the development of epistemological understanding is largely neglected in current curricula in formal post-16 education
Particle phenomenology on noncommutative spacetime
We introduce particle phenomenology on the noncommutative spacetime called
the Groenewold-Moyal plane. The length scale of spcetime noncommutativity is
constrained from the CPT violation measurements in system
and difference of . The system
provides an upper bound on the length scale of spacetime noncommutativity of
the order of , corresponding to a lower energy bound
of the order of . The difference of constrains the noncommutativity length scale to be of the order of
, corresponding to a lower energy bound of the order
of .
We also present the phenomenology of the electromagnetic interaction of
electrons and nucleons at the tree level in the noncommutative spacetime. We
show that the distributions of charge and magnetization of nucleons are
affected by spacetime noncommutativity. The analytic properties of
electromagnetic form factors are also changed and it may give rise to
interesting experimental signals.Comment: 10 pages, 3 figures. Published versio
Stringent Phenomenological Investigation into Heterotic String Optical Unification
For the weakly coupled heterotic string (WCHS) there is a well-known factor
of twenty conflict between the minimum string coupling unification scale,
Lambda_H ~5x10^(17) GeV, and the projected MSSM unification scale, Lambda_U ~
2.5x10^(16) GeV, assuming an intermediate scale desert (ISD). Renormalization
effects of intermediate scale MSSM-charged exotics (ISME) (endemic to
quasi-realistic string models) can resolve this issue, pushing the MSSM scale
up to the string scale. However, for a generic string model, this implies that
the projected Lambda_U unification under ISD is accidental. If the true
unification scale is 5.0x10^(17) GeV, is it possible that illusionary
unification at 2.5x10^(17) GeV in the ISD scenario is not accidental? If it is
not, then under what conditions would the assumption of ISME in a WCHS model
imply apparent unification at Lambda_U when ISD is falsely assumed? Geidt's
"optical unification" suggests that Lambda_U is not accidental, by offering a
mechanism whereby a generic MSSM scale Lambda_U < Lambda_H is guaranteed. A
WCHS model was constructed that offers the possibility of optical unification,
depending on the availability of anomaly-cancelling flat directions meeting
certain requirements. This paper reports on the systematic investigation of the
optical unification properties of the set of stringent flat directions of this
model. Stringent flat directions can be guaranteed to be F-flat to all finite
order (or to at least a given finite order consistent with electroweak scale
supersymmetry breaking) and can be viewed as the likely roots of more general
flat directions. Analysis of the phenomenology of stringent flat directions
gives an indication of the remaining optical unification phenomenology that
must be garnered by flat directions developed from them.Comment: standard latex, 18 pages of tex
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