Ballistic skin simulant

Floods are the most common natural disasters, causing thousands of casualties every year in the world. In particular, flash flood events are particularly deadly because of the short timescales on which they occur. Most casualties could be avoided with advance warning, for which real time monitoring is critical. While satellite-based high resolution weather forecasts can help predict floods to a certain extent, they are not reliable enough, as flood models depend on a large number of parameters that cannot be estimated beforehand. In this article, we present a novel flood sensing architecture to monitor large scale desert hydrological basins surrounding metropolitan areas, based on unmanned air vehicles. The system relies on Lagrangian (mobile) microsensors, that are released by a swarm of UAVs. A preliminary testbed implementing this technology is briefly described, and future research directions and problems are discussed.

A UAV based system for real time flash flood monitoring in desert environments using Lagrangian microsensors

A 3-D (cube-shaped) Lagrangian sensor, inkjet printed on a paper substrate, is presented for the first time. The sensor comprises a transmitter chip with a microcontroller completely embedded in the cube, along with a $1.5 \lambda _{0}$ dipole that is uniquely implemented on all the faces of the cube to achieve a near isotropic radiation pattern. The sensor has been designed to operate both in the air as well as water (half immersed) for real-time flood monitoring. The sensor weighs 1.8 gm and measures 13 mm $\,\times\,$ 13 mm $\,\times\,$ 13 mm, and each side of the cube corresponds to only $0.1 \lambda _{0}$ (at 2.4 GHz). The printed circuit board is also inkjet-printed on paper substrate to make the sensor light weight and buoyant. Issues related to the bending of inkjet-printed tracks and integration of the transmitter chip in the cube are discussed. The Lagrangian sensor is designed to operate in a wireless sensor network and field tests have confirmed that it can communicate up to a distance of 100 m while in the air and up to 50 m while half immersed in water.

An Inkjet-Printed Buoyant 3-D Lagrangian Sensor for Real-Time Flood Monitoring

Head injury by gunshots from blank cartridges.

Gunshot injuries as a topic of medicolegal research in the German-speaking countries from the beginning of the 20th century up to the present time

The literature cites values between approx. 50 to as critical velocities for spherical or ogival projectiles. This test was designed to determine the general validity of these values. “Critical velocity” is defined as that velocity, below which no penetration of the skin occurs. A series of 212 test shots was fired after the powder storage chambers of caliber 9 mm and caliber .45 cartridge cases were altered. With the appropriate charges, velocities varying between 50 and 100 m per sec were achieved. The shots were fired orthogonally into the muscle tissue of the upper thigh of corpses and into a combination of human skin + Mipoplast®. The skin was tightened in a wooden frame and a block of Mipoplast® was directly attached. (Preliminary tests showed that projectiles nearly had the same penetration power in Mipoplast® as in muscle tissue.) The projectile velocities were determined by a „shoot-velociter Re-Tronik“ with a resolving power of 10−6 sec. Projectiles were considered as having penetrated the skin, when they entered the epidermis for a distance equal to the caliber diameter. In order to determine a ballistic coefficient and a conversion factor, the depth of penetration into muscle tissue of the upper thigh or into Mipoplast® respectively was measured. The following bullets were used in the tests: 9 mm :lead ball 5.3 g lead, round nose projectile with a short cylindrical portion, 6.2 g lead, round nose projectile with a long cylindrical portion, 10.6 g conical, flat nose projectile 7.9 g conical, pointed nose projectile 7.9 g caliber. 45 : lead ball 9 g lead, round nose with a cylindrical portion, 14.7 g and finally a 4 nun lead ball. 47 g. The projectiles were fired from a Walther pistol P 38, caliber 9 mm Parabellum, a colt pistol, Government 1911 A1, caliber .45 ACP and from a revolver Rohm RG caliber 4 mm Rdz. The tests results permit three functional evaluations per series: (1) optimum parabola of second order, (2) optimum line (linear regression), (3) logarithmic function (log. nat.) The following results were obtained: The penetration power of a projectile does not depend primarily on its velocity, shape or cross-sectional load, but is determined by its mass. The following conclusions could be drawn, concerning lead projectiles fired by us: The greater the mass of a projectile, the lower the „critical velocity“ (vcr = 162.1 • e−629 m) The conversion factor for the penetration power of the examined projectiles comparing skin/Mipoplast® and skin/muscle tissue was determined to be 1.2, i. e. the depth of penetration into skin and muscle tissue is 1.2 times greater than into skin + Mipoplast ®. An evaluation of these results shows a “loop-hole” in the Gun Control Act, since the legal requirements for the unrestricted acquisition of firearms only considers the kinetic energy of the projectile (less than 7.5 J). However, all lead ball ammunition with diameters of less than 6.2 mm definitely does penetrate the skin at that energy level. Another conclusion is that projectiles fired from unlicensed weapons such as BB guns operated by air pressure, spring or CO2-cartridge (caliber approx. 4.5 mm) can achieve penetration with as little energy as 4 J. Even if one wants to maintain the present differentiation between exempted weapons and weapons covered by the Gun Control Act, based on the energy level of 7.5 J, the legislature would have to establish a minimum mass for the projectiles. Considering the results obtained, the present limitation of the kinetic energy of the projectiles of 7.5 J alone does not guarantee the level of harmlessness the present law supposes. A projectile mass of less than 1.4 g and a kinetic energy of 7.5 J can reach a level of danger that up now has not been recognized by the legislature. Those findings ought to be considered when licensing weapons according to Para 21 and 25 WaffG (Gun Control Act of the Federal Republic of Germany) as well when prohibiting weapons according to Para 37 WaffG and Para 8, Section 1, Number 1, of the first WaffV (Weapon Regulations).

Experiments on the penetration power of various bullets into skin and muscle tissue

Auf Grund von 2 Fallen mit teils schweren bzw. todlichen Verletzungen nach Schus mit einem Schreckschus-Gasrevolver bzw. -Pistole wurde die Gefahrlichkeit dieser Waffen experimentell uberpruft und festgestellt, das mit den bisher ublichen Platzpatronen todliche Verletzungen moglich sind.

[Mortal injuries after shots with a pistol of gas (author's transl)].

Verschiedene Modelle der “freien” Revolver 4 mm lang Randzunder wurden im Originalzustand hinsichtlich ihrer Gefahrlichkeit uberpruft. Parallel zu Messungen der Bewegungsenergien der Geschosse wurden Leichenversuche durchgefuhrt. Bei Verwendung von Waffen im Originalzustand lagen die Bewegungsenergien mit Originalmunition unter der gesetzlichen Grenze von 7,5 J. Todliche Verletzungen mit Lungen- und Herzschussen konnten mit jeder Waffe erzielt werden; in einem Fall kam es zur Penetration des os temporale uber einer Gefasusur. Durch Verschlus der Gasdruckentlastungszuge mittels einfachen Zweikomponentenklebers (an einer Waffe demonstriert) konnte die Bewegungsenergie der Geschosse um 45 % gesteigert werden. Erfolgte dazu noch eine Anderung an der Munition durch einfaches Einfullen von zusatzlichem Treibladungsmittel, so konnte sogar eine Steigerung um ca. 220 % festgestellt werden. Alleinige Anderung an den Patronen in der vorgeschriebenen Weise erbrachten mit Waffen im Originalzustand eine Steigerung um ca. 75%. In jedem Fall wurden hierbei todliche Verletzungen im Brustkorbbereich und am Kopf erzielt. Nach diesen Untersuchungsergebnissen wurden Vorschlage zur Anderung des Bundeswaffengesetzes und weiterer rechtlicher Masnahmen unterbreitet.

Die Gefährlichkeit der „freien“ 4 mm Faustfeuerwaffen

Die kritischen Anmerkungen von D a m m e r m a n n k6nnen nicht unwidersprochen bleiben. Sie stfitzen sich zum Teil auf eine nicht korrekte Wiedergabe unserer Ausffihrungen und auf eine Formul ierung in der Zusammenfassung, die erkennbar die Gesamtaussage unserer Untersuchungen nicht ganz exakt wiedergibt. Zugleich machen sie deutlich, dab D a m m e r m a n n offenbar mit einer vorgefa6ten Meinung an die Wt~rdigung der Ergebnisse herangegangen ist. Er h/itte sonst nicht allein aufgrund eines wohl nicht sehr glficklich formulierten Satzes in der Zusammenfassung sein Urteil gef'~illt, sondern bei objektiv kritischer Wt~rdigung des Gesamtinhaltes der Ausft~hrungen festgestellt, dab unserer These wie sie immer wieder zum Ausdruck kommt lautet:

W. Sattler

Papers

Experiments on the penetration power of various bullets into skin and muscle tissue

[Mortal injuries after shots with a pistol of gas (author's transl)].

Die Gefährlichkeit der „freien“ 4 mm Faustfeuerwaffen

Erwiderung zur Stellungnahme von Dr. W. Dammermann