Sealed Beam Research Articles

Periodic Vibrations of a Beam with Rigidly Sealed Ends

We study the problem of searching periodic solutions to the Euler–Bernoulli equation governing vibrations of a beam with the boundary conditions corresponding to the case of rigidly sealed beam ends. The nonlinear term satisfies the nonresonance condition at infinity. We establish the existence and uniqueness of a solution. To prove the results, we use topological methods (the Leray–Schauder principle) as well as variational methods (the mountain pass theorem).

Microbial induced calcium carbonate precipitation study using Bacillus subtilis with application to self-healing concrete preparation and characterization

This study aimed to develop novel bacteria-based self-healing concrete by microbial induced calcium carbonate precipitation mechanism. A group of spore-forming bacterium related with gen Bacillus subtilis were selected for cultivation at elevated pH solution. The derived alkali-resistant Bacillus subtilis M9 was applied for biomineralization test whereas the precipitate mineral was calcium carbonate in calcite phase according to X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) results. With B. subtilis M9 as the healing agent, the self-healing concrete beam specimens were then prepared by incorporating polyvinyl alcohol fibers. Air-entraining agent was utilized to yield micro pores in cement paste mixture to provide ecological niches for microbe. 3-point-bending test was conducted to form 0.3-mm-width cracks on the beam bottom. After 28 days curing, the micro cracks were autonomously healed with calcium carbonate precipitation fillings due to the bacteria metabolic activity. The sequent SEM tests implied that calcite is the dominant mineral phase with some bacterial imprints on the crystal surface. Furthermore, flexural strength of the sealed beam subjected to repeated bending was enhanced by about 14% compared to residual flexural strength. The beam flexural strength recover was realized by remediation of the cracks in matrix as well as repairing of fiber–matrix interface bond.

Assessment of Sag Curve Design Criteria considering Modern Headlamp Performance

For more than 50 years, headlight sight distance has been one method for calculating the length of sag vertical curves; the others are passenger comfort, drainage control, and general appearance. The headlight sight distance is based on a 1° upward divergence of the headlamp beam. Over the past 20 years, headlamps have transitioned from being 100% sealed beam to modern replaceable bulb headlamps that project less light above the horizontal plane than the sealed-beam headlamps that are the basis for sag curve design. This paper describes theoretical and field measurements of the illuminance levels provided by sealed-beam and modern headlamps. The results of the analysis indicate that modern headlamps provide significantly less light above the horizontal than sealed-beam headlamps, indicating a potential need to modify the design equations for sag vertical curves. According to the theoretical analysis, the upward divergent headlamp angle used in the sag curve design equation should be reduced from 1° to between 0.75° and 0.90°. The field analysis indicated a significant difference in illuminance levels from the theoretical analysis, but the results also indicate a need to reduce the headlamp angle used in sag curve design.

How Modern Headlamp Performance Impacts Sag Vertical Curve Design

For over 50 years, the basis for calculating the length of sag vertical curves has been the sight distance based on a 1° upward divergence of the headlamp beam. Over the last 20 years, headlamps have transitioned from being 100% sealed beam to modern replaceable bulb headlamps that project less light above the horizontal plane compared to the sealed beam headlamps that are the basis for the sag curve design. This paper analyzes the performance of modern headlamps with respect to sag vertical curve design by calculating the amount of illumination reaching the pavement in a sag curve. The analysis indicates that the headlamp beam angle used to calculate sag curve length should change from 1 to 0.75° to provide an illuminance level with modern headlamps that is equal to the illuminance provided by sealed beam headlamps. Such a change would increase the K values for sag curve design from 13, 30, and 55 to 15, 37, and 70 for design speeds of 110, 80, and 50 km/h, respectively.

Let Light Be There

This article focuses on structures that today have moved completely away from sealed beam assemblies, relying instead on aerodynamic housings whose shapes are designed to flow with the contours of car bodies. Even before automotive high-intensity discharge (HID) lighting arrived, halogen bulbs had sought independence from their housings not only to free up lens shapes to the whimsy of stylists but to reduce drag as well. The advantage of, and trouble with, HID lighting is that it more than triples the output of halogen bulbs while consuming fewer watts. The light from an HID lamp, said to be closer to the hue of natural light and thus thought to be better at illuminating a rain-wrapped road, comes from an electrode-ignited xenon atmosphere. European lighting manufacturers, such as Hella, work in conjunction with automakers, other lighting manufacturers, and research groups in demonstrating for regulators the technology that might one day will be required on cars there.

Early vacuum systems and process descriptions used to deposit optical coatings

A review will be given of the equipment and evaporative processes used to manufacture optical coatings prior to the formation of the Committee on Vacuum Techniques in 1953. Processes to be covered: sealed beam headlights; antireflection films (using hot substrates and electron beamed substrates); German SiO coated mirrors; coating of Schmidt mirrors using a record changer in system; the Mt. Palomar astronomical mirror; hot and cold filters. Present day sputtering of large architectural windows will be described.

Feasibility of end to end phase shift correction from the outside of sealed cesium beam tubes

Summary It is well known that a frequency shift mceable to asymmetry of the microwave resonator occurs in atomic beam frequency standards making use of Ramsey’s double interaction technique. The shift is due to the phase difference which then appears between the fields interacting with the atoms in the two regions. The atoms in fact cannot distinguish the latter from the phase accumulated by a frequency offset during the time of flight between the two cavities. Beam reversal experiments can measure such end-to-end phase difference if it can be assumed constant for the two beam directions. In that case in fact a beam reversal simply changes the sign of the effect. However, this technique can only be applied with predisposed laboratory type primary standards, while in the case of unidirectional beams any accuracy assessment on end-toend phase shift has been traditionally made by relying on mechanical specifications and aimming, and on elecmcal length measurements, during cavity manufacturing. That a correction of end-to-end phase shift might be possible by acting from the outside of a sealed tube has been suggested nxently [ 13, by noting that not just the two arms of the Ramsey cavity, but the microwave structure as a whole, contribute with their asymmetry to the occurrence of the problem. A formula for the end-toend phase difference was found, which includes the asymmetry of the feeding junction at the center of the Ramsey structure, and reduces to the traditional formula in the case of a symmetric junction. It was therefore proposed that a correction of arm asymmetry could be tried by introducing a compensating asymmetry in the “symmetric” arm of the feeding T-junction. Such asymmetry should be calibrated so that the asymmemc superior cut-off modes that it excites produce at the junction the desiredphase difference between the waves launched in the two opposite directions. In this paper an electromagnetic calculation is carried out of the asymmetry induced in an E-plane waveguide T-junction by an asymmetric iris in the feeding port. A comparison with experimental results is given. It is shown that compensation of end-to-end phase shift is possible in this way, and that shifts of few parts in A discussion about how well the absolute size of the effect can be judged by measuring the structure in reflection is also given, and the relevance that this has toward accuracy statements on unidirectional beams is underlined. 1013 can be reduced to below iX1013.

Determination of the Temperature of the Filament Adjacent to the Incandescent Filament in a Double Beam Headlight

The temperature of the off filament adjacent to the incandescent filament in a double beam headlight was measured in an atmosphere of 88% argon and 12% nitrogen at a pressure of 600 mm mercury. Temperatures in the range necessary to melt sealed beam glass on a filament were observed.

A testing jig for sealed beam monitors

The dose received by a patient during radiotherapy on a linear accelerator is monitored by an ionisation chamber. The beam monitor in a Philips SL-75 accelerator is a dry-nitrogen-filled sealed box containing a pair of parallel-plate transmission ionisation chambers. If the monitor develops an air leak the charge measured by the chambers will fluctuate with ambient conditions resulting in variations in treatment dose per fraction. This note describes a self-contained testing system to differentiate between sealed and leaking beam monitors, but this technique necessitates the removal of the monitor from the accelerator.

Apparatus for measuring the stopping power of active materials evaporated i n s i t u and characterized by Auger electron spectrometry and Rutherford backscattering

An ultrahigh-vacuum scattering chamber working in the low 10−9-mbar range is described. It is attached to a standard O-ring sealed beam transport system of an electrostatic accelerator. Twelve targets can be prepared in situ, one by one, by evaporating the material onto backings, which are mounted on tiltable target holders on a wheel. Backscattering spectra are obtained from these targets and the stopping cross section is deduced from their widths. A cooled high-resolution surface barrier detector is used for this purpose. The integral concentrations of light impurities in the target are obtained using Rutherford backscattering (RBS), whereas Auger electron spectrometry (AES) together with a sputtering device is used to determine the depth composition. As a test of the assembly we determined the stopping power of aluminum for protons and deuterons, respectively. The results are compared to published tables based upon fits to experiments. The influence of impurities on the result is discussed for an aluminum target prepared under standard evaporation conditions.

The Effect of Impact on the Filaments of Quartz Halogen Headlamps

ABSTRACTQuartz halogen headlamps, unlike the older types of sealed beam headlamps, often have filaments oriented parallel to the forward direction of travel of the vehicle. Both compression and stretching of filament coils may be observed when vehicles equipped with quartz halogen headlamps are involved in collisions. The conditions under which these distortions occur have been studied by conducting impact tests on quartz halogen lamps under known conditions of velocity, illumination and impact angle. The results show that filament coil compression distortion was produced by the “head-on” impact of illuminated filaments, whereas coil stretching distortions were produced by impact of illuminated filaments at any angle. Further, if impact forces are of sufficient magnitude, an illuminated filament in an intact quartz halogen lamp can break.

Accessible calibration technique for mechanical impedance measurements

A velocity pickup for stereo disk playback can be calibrated for magnitude of velocity response by using commercially available test records modulated by pure sinusoidal signals. The records may be calibrated independently by using a collimated light beam (sealed beam headlamp) and measuring (with divider and ruler) the extent of the “Christmas Tree” pattern reflected from the grooves. During playback at measured speeds the record becomes a source of calibrated velocity amplitude for each of the pickup channels. Summing and differencing the pickup outputs convert right and left to vertical and horizontal outputs. The phase difference between the stylus velocity and the electrical output of the pickup is calibrated by placing the cartridge tip in a dimple cut into the ground electrode of a piezoelectric force transducer driven electrically well below its resonant frequency. The driving voltage and the pickup output then exhibit the same phase relation as the groove displacement and the pickup output. The force/velocity ratio measuring system is calibrated as a function of frequency by using known masses as loads. For measuring an unknown mechanical impedance, the force pickup is interposed between a driver and the load, with the pickup stylus mounted either in the dimple in the electrode, or on the surface of the load. [This work has been performed using the facilities of the National Bureau of Standards.]

UHV facility for metal–semiconductor thin-film studies

A unique multifunction apparatus consisting of a surface analysis chamber operating at 1×10−8 Pa connected by a 4.5-m-long beam line to a 3.75-MeV Van de Graaff accelerator operating at 1×10−4 Pa is described. The bakeable, all-metal sealed beam line contains collimating, blocking, focusing, and steering facilities for the MeV ion beam and is differentially pumped with a turbomolecular pump to 4×10−7 Pa after a mild (100°C) bakeout. The chamber contains surface preparation equipment, a double-pass CMA for AES and ELS, and facilities for metal evaporation at P?8×10−7 Pa from an electron-beam source while simultaneously performing MEED. A specially designed manipulator allows samples to be cleaned, annealed, and characterized prior to in situ evaporation. The resulting metal–semiconductor couple may also be annealed in situ and characterized by AES, MEED, and Rutherford Backscattering Spectroscopy.

Electronically Scannable Semiconductor Laser Device

An electronically scannable electron-beam-pumped semicon-ductor laser device is described which provides laser emission from more than 1000 X 1000 randomly addressable spots. The device consists of a permanently sealed electron beam tube about 50 cm long. Attached to the inside of the face-plate is a 30 um thick cadmium sulfide single crystal wafer with typical lateral dimensions of 28 mm X 28 mm, which serves as the active laser element. Using a 50 ns pulsed elec-tron beam current of up to 2 mA, with an accelerating poten-tial of about 50 keV, laser emission is produced in a direction essentially coaxial with the pumping electron beam. A laser spot diameter of 25 um can be achieved with these devices. The emitted radiation is typically confined to a symmetric cone with a half angle less than 0.1 rad. The laser tube is capable of operation at room temperature or, for greater power output, may be conveniently cooled with conventional refrigeration to about -50°C. At this temperature, peak power outputs in excess of 5 watts have been produced from CdS at 515 nm wavelength. In preliminary tests, laser tubes have been operated at repetition rates up to 400 kHz for more than 2000 hours without significant decrease in laser emission. Applications of such devices include display, COM/CIM, and optically addressed holographic memories.

A high performance graphic arts lamp

A very high optical performance can be achieved by enclosing a metal halide lamp, suitably doped for the printing and reprographics industry, in a sealed beam reflector and refractor enclosure. The period of exposure needed under this very actinic light source is considerably shorter than that required by pulsed xenon, mercury vapour or the carbon arc and its enclosed optics ensure an excellent u.v. maintenance throughout a long life. Designed to be used on a 240 V a.c. supply the lamp consumes 400 watts and operates with a choke ballast and starter unit.

A Study of the Refractive Index Variations Within and Between Sealed Beam Headlights Using a Precise Method

Abstract One of the primary goals of the forensic scientist is to be able to individualize physical evidence. Associated with this goal is the underlying assumption that no two things are exactly alike. Individualization has been obtained if it can be unequivocally stated that this fingerprint is that of John Doe, or that this piece of glass is from this sealed beam head-lamp and no other. Unfortunately, due to practical limitations, individualization is not always possible. In such a case the forensic scientist must examine all information available and then make an “estimate of the situation” [1] often based upon his past experience. The purpose of this paper is to aid the forensic scientist so that he may make a better estimate of the forensic value of automobile headlamp glass when confronted with this type of evidence.

Developments in Light Sources for Filming and Projection

AbstractThe paper is a review of recent developments in light sources for filming and projection in both the amateur and the professional fields. Three recent major technical advances are described, namely: Halogen Lamps, Sealed Beam Lamps and Dichroic coating, as applied to lamps, are dealt with in some detail. The most important lamp designs for each particular application are also reviewed

Non-Glare Headlight with a Sodium Nitrate Polarizer as a Filter

With a view of obtaining a polarization headlight which is sufficiently bright for a free field driving and at the same time is dim to a driver of an oncoming vehicle who views the headlight through an analyser placed in the crossed position to the polarizer over this headlight, a set of polarization headlight system is constructed. It consists of a sealed beam headlamp with a smooth front cover glass, having the same 50 watt filament as the conventional sealed beam one, a cylindrical lens system over a part of the aperture and a sodium nitrate polarization plate. Illuminance of this set satisfies the Japanese Industrial Standard (JIS), which is equivalent to the SAE in America. Its maximum light intensity, 26200 Cd, is about 2.7 times as high as that of the known type of polarization headlight (9800 Cd) with the use of “Dichrom” or “Polaroid”, and is about 86 per cent of 30600 Cd of the conventional sealed beam headlight.

Glass for Modern Electric Lamps

Glass for electric lamps must have many different properties, e.g. transparency, resistance to heat, ability to form hermetic seals with the current leads, resistance to chemical attack and weathering, and different types of lamps require glasses differing in composition. Appropriate methods of glass melting are described in this paper, and the necessary properties of glass for tungsten lamp bulbs, fluorescent tubes, pinches and for sealed beam headlamps are discussed; appropriate compositions and forming methods are also given. Production methods for glass and quartz tubes for high pressure discharge lamps are outlined and the particular problems of sodium lamps—glass blackening and argon absorption—are discussed in detail.

Mating Behavior of the Ram in the One-Sire Pen

Thirty-two breeding pens containing one ram and 18 to 38 ewes each were observed continuously for 7-day periods for mating and related activity in late fall at Dubois, Idaho. Variation in air temperature, wind velocity, cloud cover, precipiation, brightness of moonlight, type of artifical light at night (sealed beam spotlight or infrared illumination), age, inbreeding, body weight, semen score and previous use had no important influence on mating behavior. Rambouillet rams appeared to be more active than either Targhee or Columbia rams. Targhees were intermediate between the other two breeds. The number of ewes in heat and individual ram differences independent of number of ewes in heat were the two most important factors affecting mating behavior in the ram. The most active ram mated 66 times in 6 days during which one or more ewes were in heat 73% of the time, as compared with 18 times for the least active ram with one or more ewes in heat 87% of the time. The average ram mated 45 times in 6 days (standard deviations=17) during which one or more ewes were in heat 70% of the time. The number of times each ewe was mated after an initial drop in the number of matings per ewe tended to remain fairly constant regardless of the number of ewes in heat. Thus, an increase in number of ewes in heat resulted in a marked increase in the number of matinges per ram per day. The number of mounts per mating was unaffected by the number of ewes in heat. Seeking time per hour was little different with one, two or three ewes in heat, but was greater when no ewes were in heat. The rams spent slightly less time lying down and eating as the number of ewes in heat increased from none to three. The time between first and second ejaculates during semen testing was not significantly correlated with number of matings per hour. However, the number of mounts per ejaculate in semen tests was significantly related to number of mounts per mating in actual service. The rams which required the fewest mounts per mating mated the most ewes on the average. Rams were more active for several hours immediately after introduction into breeding pens than later. Stimuli such as initial introduction into breeding, number of ewes in heat, feeding time and the need for a rather definite amount of rest unbothered by daylight disturbances had greater influence on mating behavior than hour of day or amount of light. None of the mating behavior characteristics of the ram studied were significantly correlated with percent of ewes lambing.