Strike Object Research Articles

On some problems in dynamic computation for thin-walled structures

This article discusses the problems of the dynamic computation for thin-walled structures such as thin plates and thin shells under impact load to find the dynamic factor mainly. In calculation we take into account the effect of the mass of the striking object and the system of thin-walled structures to be struck and transform the distributed mass of thin-walled structures into only one concentrated “equivalent mass” by the method of reduced mass. Accordingly we derive the dynamic factor for the system of thin-walled structures under impact load.

Dynamics and structural damage of tanker ships running aground

A finite element method is described which models a ship impacting against another object. The ship is modeled as a beam which has the same flexibility, mass distribution and floatation properties as the ship. The ship structure may collapse locally during the ongoing collision process as also may the struck object. A number of collision scenarios involving the collision of a large tanker-ship with a submerged rigid rock are investigated. The significance of ship speed on the extent and nature of the damage to the hull is established.

Some problems for dynamic computation of closed cylindrical shell due to axial impact load

The present paper treats some of the problems for dynamic computation of closed cylindrical shell due to an axial impact load, including the calculations of the dynamic stresses and the problems of stability. It analyses the changes of the momentums and the energy in the impact process, takes into account the effect of the mass of the striking object and the system of the closed cylindrical shell to be struck, turns the distributed mass of the total cylindrical shell into an “equivalent mass” being concentrated on only at one end of the shell by using the way of reduced mass, and accordingly derives the dynamic factor of the closed cylindrical shell under the axial impact load, hence resolves the questions of calculation of the dynamic stresses in the loaded case mentioned above and found out the critical loading.

Northeastern Ohio trauma study III: Incidence of fractures

To determine the frequency with which fractures are encountered in emergency care and to estimate the incidence of fractures in a well-defined population, a population-based sample of emergency department (ED) visits was examined. Eleven percent of ED visits for trauma involved fractures. The incidence of fractures was 21 per 1,000 persons per year and had two peaks, the first at ages 10 to 14 and the second at ages greater than 60. Among young people, falls (often related to sports or recreation), striking objects, motor vehicle injuries, and assaults were the major causes of fractures. Among the elderly, falls caused 87% of all fractures.

The three wheeler--a menace to the preadolescent child.

Children riding three-wheeled motorcycles have recently become victims of serious or fatal accidents. Twelve children (aged 3 to 12 years, mean, 8.7 years) all white, sustained serious or fatal injuries as a result of striking objects or overturning while riding these vehicles. The injured children were preadolescent, white, rural, male, and from relatively affluent families. Most injuries were to the head and upper torso causing severe cosmetic and functional deficits. Our experience suggests the need for better regulations for these vehicles when being ridden by children.

Assessment of large displacement of a rigid-plastic shell withholding a localized impact

Abstract A method is derived allowing to assess large deflection of a rotationally-symmetric rigid-plastic shell impacted by a concentrated mass. Assuming a kinematically admissible mechanism of motion of the deforming portion of the shell the final shape of the shell and the time to rest are evaluated. The principle of virtual work is employed to derive the non-linear differential equation of motion of the impacting mass withheld by the shell. The maximum central deflection in terms of kinetic energy of the striking mass and of the dissipative properties of the shell is given. For a point impact an analytic solution is obtained. A numerical technique is used in the case of impact by a finite stamp and the central deflection of the shell is plotted in terms of velocity, mass and kinetic energy of the striking object.

Cunobelin's Gold

Amongst the most striking objects to survive from the three decades preceding the Roman conquest of Britain are the magnificent series of gold coins of Cunobelin. They are numerous and display an exceptional range of styles, from the traditional through the barbaric to the severely classical. Enough remain to permit a thorough die study, from which some interesting conclusions for the period can be drawn.

Mechanisms for Communication

Animals use many different methods to produce communication signals even within a single sensory modality. For example, sounds may be produced by the passage of air through special organs as in the mammalian larynx and avian syrinx, by rubbing appendages against each other like insect legs and wings, and by striking objects in the environment as in woodpeckers.

Pericardial effusion complicating acute tubular necrosis.

Goodner and Brown's 1 report based on autopsy findings in 2 cases of cardiac tamponade in uremic pericarditis emphasized that uremic pericarditis should be considered in the differential diagnosis of cardiac tamponade. Eight months later Guild, Bray, and Merrill 2 reported the first 2 cases of uremic pericarditis in which the diagnosis of pericardial effusion was made before death, and removal of pericardial fluid resulted in striking objective and subjective improvement. Goodner and Brown commented that since uremic pericarditis is such a poor prognostic sign in chronic renal disease, pericardiocentesis would probably not yield more than transient prolongation of life. They suggested, however, that cardiac tamponade might occur in a potentially reversible form of renal failure and that here its recognition and treatment might be life-saving. This report describes the first 2 cases, 1 certain and 1 probable, of massive pericardial effusion complicating a potentially reversible form of renal failure,

Tuberculous peritonitis treated with streptomycin

Abstract 1.1. Twenty-six patients with tuberculous peritonitis were treated with streptomycin. 2.2. Twenty-five of the twenty-six patients responded favorably to streptomycin therapy. One patient with coexisting pulmonary tuberculosis failed to respond and died. 3.3. Four of the improved patients had a relapse. Two of them responded to a second course of streptomycin; one failed to respond. One patient was not retreated and died following a relapse. 4.4. A majority of the patients had been seriously ill and many were chronically ill. The uniformity and rapidity of response, the subsidence of fever and abdominal symptoms, the general improvement, the striking gross objective improvement observed in three follow-up laparotomies and the fact that six patients have returned to work are clear indications of the effect of the drug. In most instances streptomycin therapy changed the trend of the disease and shortened the disease process. 5.5. The duration and type of peritoneal involvement did not influence demonstrably the response to therapy. 6.6. Tuberculosis of the peritoneum responded as well as or better than coexisting tuberculous lesions elsewhere. 7.7. Streptomycin did not prevent the development of new lesions. 8.8. Comparable results were obtained with daily administration of 1 or 2 gm. of the antibiotic. The smallest amount of streptomycin needed for the arrest of the disease is yet to be determined. 9.9. Although immediate improvement following streptomycin therapy was excellent in most cases, continued observations will be necessary to determine the efficacy of streptomycin in the ultimate control of the disease. The development of new extraperitoneal lesions during and after therapy and the persistence of histologic evidence of tuberculosis in two cases make the prognosis extremely guarded.

THE MECHANISM AND MANAGEMENT OF INJURIES OF THE HEAD

Great strides have been made in the study of the mechanism and management of injuries of the head during the past ten years. In the present paper it is proposed that the more important of these studies be analyzed. MECHANISM OF CRANIOCEREBRAL TRAUMA Injury to the head may occur by direct or indirect violence. In a direct blow the head is relatively fixed and the striking object is in motion. A direct blow may cause compression of the intracranial contents by deformation of the skull, and it may set the head to motion (acceleration). In indirect blows the head in motion comes in contact with a nonmoving or slower moving object. Under these circumstances, compression and deceleration may obtain. Compression, deceleration and acceleration frequently coexist in the usual injuries such as auto accidents, falls, etc. 1 With direct blows the lesion is more likely to be limited to the head,

Museums and the Research Worker

SOME aspects of recent criticism of ethnographical collections in the museums of Great Britain are considered on p. 179 of this issue of NATURE. It cannot be emphasized too frequently that the great national collections—the question under discussion cannot affect the smaller museums except in so far as they are prepared to specialize—being supported out of public funds, it is their bounden duty to perform a function of public utility ; whether that may be, as is now generally required of them, that they should take their share in making efficient and supplementing the machinery of general education, or the more highly specialized function of assisting the research worker. To the latter rather than to an attachment to a traditional system must be attributed the classificatory organization which has been subjected to criticism. For it must not be forgotten that the great national collections, as well as the smaller ethnographical museums, some highly specialized, such as the Pitt-Rivers Museum at Oxford, the Museum of Archæology and Ethnology at Cambridge, or the Manchester University Museum, have been the laboratories for the scientific researches of the technologist in the broader sense, the student of material culture. It is upon this class of evidence that the archæologist, the ethnologist and the student of early culture generally so largely rely. In the modern museum building, however, the trend of development is to make provision for the worker in technological research by withdrawing the bulk of the material in which he is interested from public exhibition, while the public galleries are given over to the more striking objects or to those of most educative value to the public. Doubtless when more space is given to our great public collections, the same method of procedure will be followed, and the public galleries will then be devoted to regional methods of display, in so far as these may have approved themselves as the most effective for purposes of instruction.

Murnpeowie (South Australia), a granular type of meteoric iron

Apreliminary account of this fine mass, weighing 2520 lb., of meteoric iron was given in 1910 by L. Laybourne Smith, who at that time was Registrar of the South Australian School of Mines and Industries in Adelaide; but the promised detailed description with chemical analysis never appeared. Except for a small piece cut off one corner (upper left-hand corner in fig. 1) the mass is preserved intact in the Museum of that Institution, and none of the material appears to have been distributed to other museums. Casts of the mass were, however, made for the South Australian Museum in Adelaide, and one of them was presented to the British Museum in 1917 (B.M. 1917,360), where in the meteorite collection it is a very striking object (fig. 1).Recently, at the suggestion of Mr. R. Bedford of the Kyancutta Museum, the Council of the South Australian School of Mines has generously presented to the British Museum a piece of this meteoric iron, together with the milling cuttings, with the request that the description of it should be completed.

Archæological News from Iraq

There is unusual archaeological activity in Iraq during the present winter and the season promises to be one of the most fruitful in the history of archaeological researches in that country. Dr. Woolley at Ur has already come upon another royal tomb which promises to rival in magnificence and importance the royal tombs which he discovered last year. In it were found the skeletons of numerous attendants who were killed and buried with their master. The tomb also contained another chariot together with the skeletons of the charioteer and of the donkeys which had drawn it. At Tarkhalan Dr. Pfeiffer, assisted by Mr. Starr and Mr. Wilenski, has continued the work begun in the previous season by Dr. Chiera under the auspices of Harvard University and the Baghdad School. At last report they had cleared out a large number of additional rooms in the great building which Dr. Chiera believed was a temple, and had found many additional tablets together with various types of pottery. One striking object was a large pottery incense-burner in the shape of a miniature house with windows and a chimney, giving us perhaps an idea of the formation of the houses of ancient Nuzi. In addition to the numerous tablets that have been discovered, an interesting, complicated, and wellthought-out system of drainage has been traced, which shows that the inhabitants of ancient Nuzi had fairly good sanitary arrangements. The work of Dr. Waterman at Ctesiphon is going steadily forward, as is that of Dr. Andrae at Seleucia. Both we understand are making important discoveries. Dr. Chiera has left America on his way to Iraq in the interest of the University of Chicago and may undertake a small excavation at Khorsabad before he returns. We understand that Mr. R. Campbell Thompson is also opening again the trenches at Nineveh where British excavators have so often in the past made important discoveries. The French are also re-opening the work at Telloh, and a German expedition is, we are informed, excavating at Warka, the ancient Erech. Miss Garrod, the discoverer of the Neanderthal remains at Shuqbah, with her party, including Mr. Franks of Harvard, recently visited Dr. Pfeiffer at Tarkhalan. Miss Garrod's party had completed for the present their excavation of paleolithic sites and caves near Suleimanieh. The party was on its way to Palestine. According to the latest announcement by Professor Langdon, the Oxford-Chicago (Field Museum) expedition at Kish has been working this season in excavations below the water level which was reached in last season's work. The water level is about nine feet higher than when the city was first founded. By exhausting the water from small areas by hydraulic devices, the excavation has been carried down to virgin soil. Near the top of the Tell are the foundations of the temple repaired by Nabonidus, who ruled from 555 to 538 B.C., and the strata from this point down to the earliest occupation of the site have been carefully noted. Some 55 feet below the well preserved walls of Nabonidus the ruins of plano-convex walls of the Sumerian type of brick now appear.

STUDIES UPON EXPERIMENTAL MEASLES

An active transmissible virus exists in the blood of measles patients during the eruptive stage of the disease. This virus produces in rabbits after intravenous injection a specific reaction analogous in all essential features to that of the human infection. Following a definite incubation period of from 2 to 5 days the animals infected show pyrexial, leucocytic, and cutaneous alterations. Fully 90 per cent of such inoculated rabbits react in a remarkable manner. The earliest constant symptom of the infection is a rise in temperature, which on the average occurs 4 days after inoculation and most probably marks the end of the incubation period. Concomitantly with this temperature rise there is a diminution in the total number of circulating leucocytes. This decrease in the number of white blood elements may be relative or may appear in the form of a well defined leucopenia. The most striking objective signs are the coryza, conjunctival injection, enanthemata, and exanthemata. The mucous membrane lesions are similar in their physical appearance to the so called Koplik spots seen in man. They occur on the buccal side of the oral cavity ranging in number from two to eight discrete hemorrhagic areas with paler centers. They appear as a rule coincidently with the temperature rise or shortly thereafter. The exanthematous lesions though occurring only in about 40 per cent of the infected animals complete the clinical syndrome in this particular experimental host. The rash may appear as early as the 3rd and as late as the 7th day after inoculation. In its early stage it is of the macular variety, appearing as a diffuse eruption which later develops into a more papular type of lesion. At this time the cutaneous manifestations appear as slightly raised, flattened, purplish red, discrete areas in the skin of the face, neck, chest, and abdomen. Repeated passage of the virus of measles through the rabbit seems to increase its virulence. A number of animals infected with such passage virus succumb in the fourth and subsequent generations, undoubtedly as the direct result of the action of the specific excitant, as in none of the animals was there cultural evidence of secondary intercurrent infection. In the animals dying presumably as a result of the specific virus grave nephritic changes were evident. It is a noteworthy fact that the pneumonia so common in fatal cases of human measles was not evident in any of the experimental animals. We believe this to be of considerable significance, especially in elucidating the direct etiological factor of the fatal pneumonias so often present in human measles cases. Apparently such infections in man can be explained purely on the basis of the destruction of normal defense barriers by the specific excitant of the infectious disease, and the lack of host resistance to the ordinary pyogenic microorganism.

The Camera in Australia

Now that most members of the overseas party of the British Association have, happily, returned safely from the meeting in Australia, it seems opportune to remind members of the scheme for the exchange of photo-graphic prints announced in the Journal (issued in Melbourne on August 12, 1914, p. 2), for which Dr. A. Holt and myself became responsible. The aim of the scheme was to economise our stock of plates and to prevent unnecessary duplicating of prints. Thus in the advance party in West Australia one member took, a photograph of one striking object, a second member of another, on the understanding that all members of the party would be able to obtain, at their own expense, copies of the prints of the photographs, either by an exchange of photographic prints taken by themselves or by payment of the cost of the print supplied. It was an essential feature of the scheme that the photographers themselves should not suffer financial loss in meeting the requests of members for prints.

Brief Notes on the Distribution of Hepaticae

I. LOPHOZIA KAURINI (Limpr.) Steph. Just before the issue of the March (1911) BRYOLOGIST containing the excellent drawings of Lophozia Kaurini by Miss Lorenz, a tew plants were found in a specimen of Preissia quadrata collected at Apostle Islands, Ashland Co., Wisconsin, in May, 1902, by Prof. C. E. Allen of the University of Wisconsin. These plants were determined by Dr. Evans as Lophozia Kaurini. A little later, in examining the material collected by the writer Oct. 3, 1910, at Black River, near Superior, Douglas Co., Wisconsin, good fruiting plants of this beautiful and rare species were again observed. In this instance also, it grew associated with Preissia quadrata, on high wet rocks along the side wall of the stream half way up the falls. The plants collected here as well as those from Apostle Islands dry a dark brown, the leaf cells are large, with arge trigones, and the leaves show blunt lobes as in the specimens collected by Miss Lorenz. The plants were fruiting and plainly paroicous and the large fully developed barrel-shaped perianth, contracted into a long beak and ciliated at the mouth, is a striking object even under a simple lens. The leaf cells when dry have a glistening appearance not unlike Calypogeia Trichomanis, except that the cell outlines are here dark and brown, instead of yellowish white. A week later while examining Prof. Allen's material from Isle Royale, Lake Superior, collected during the summer of 1901, the writer again found the species, this time mostly in a sterile condition. It would be interesting in view of the later facts concerning Lophozia badensis, Lophozia Kaurini and Lophozia Muelleri to examine all the Lophozia Muelleri material in the various herbaria. The writer would also suggest a close scrutiny of all the Preissia quadrata specimens, as it is a very commonly associated species. Apostle Islands are about 75 miles east of Superior, Wis., on the south shore; Isle Royale is about 200 miles northeast on the north shore of Lake Superior. These three localities make a third regional station for Lophozia Kaurini for North America, the other two being Yukon and Vermont.

Our Astronomical Column

RECENT BRILLIANT FIREBALLS.—Mr. W. F. Denning writes:—A brilliant Quadrantid passed horizontally, with a slow motion and long course, along the W. heavens on January 6, 8h. 40m. Other fine meteors were noticed on January 7, 9h 27m.; on January 11, 5h. 30m., 7h. 4om., 8h. 11m.; January 13, 9h. 48m.; January 17, 8h. 20m.; January 19, 5h. 50m., 7h. 50m., &c. But the most striking object of all was that of January 11, 8h. 11m., and a large number of descriptions of the appearance and position of this brilliant visitor have come to hand. From these I have worked out the real path as follows:—Height, 58 to 29 miles over Llandovery to Usk, South Wales; length of path, 52 miles; velocity per second, 13 miles; radiant point, 332°+36°; earth point, Chippenham, Wilts. The meteor was estimated by Mr. H. Chapman, of Newtown, N. Wales, as brighter than the full moon, and it gave two flashes of sufficient intensity to light up the firmament and terrestrial objects for several seconds. The meteor moved slowly from a radiant in the western sky. Several of the observers describe the motion as undulatory, as though the object o experienced some difficulty in penetrating our dense atmosphere. The radiant point is not conformable with that of any known meteoric shower, but it falls in the same place as that of an active stream or streams visible in the months of July, August, and September.

A Long-lived Solar Halo

THERE has been visible here to-day a solar halo remarkable both for its vivid intensity and for its protracted duration. It was first noticed by me at 12.35 p.m. It then formed an unbroken ring, of which the most intensely luminous portion was to the south of the sun, and the least luminous portion to the west-north-west. Half an hour later the southern and northern quadrants of the circle were equally bright, but the northern appeared the more compact and definite; meanwhile, the eastern and western portions continued comparatively feeble, more especially the latter. These conditions remained unchanged for fully 11/2 hours! After 2.15 p.m. the northern segment of the halo was alone conspicuous, and after 3.30 p.m. the ring was never again complete, though two mock suns (to the southward and eastward respectively) still testified to the original configuration. By 4.50 p.m. nothing remained but a diffused, pale rainbow-coloured mock-sun to the north of the sun; but after 5.15 p.m. this became less indefinite, and by 6 p.m. fully a semicircle of a halo was again traceable above the sun, but this faded gradually, nothing surviving after about 6.20 p.m. The unusually strong tone of rusty orange colouring, and the conspicuous darkness of the region enclosed, made the halo an unusually striking object when at its best (12.30 to 2 p.m.).

II.—Cupressinoxylon Hookeri, Sp. Nov., A Large Silicified Tree from Tasmania

One of the most striking objects exhibited in the Gallery of Fossil Plant remains in the Geological Department of the British Museum (Natural History) is a large trunk of a Coniferous tree from Tasmania, of which a photograph is reproduced on Plate I. This specimen is one of the largest in the gallery, being nearly nine feet in height, and three feet in diameter. The woody tissues are in excellent preservation, the specimen being silicified, and in part opalized.