On The Accuracy Of Calculation Of The Impedance Spectra Of Woodwind Instruments

Most woodwind instruments in museums may not be played, because of the risk of damage. However, if the acoustic impedance spectra (tube resonances) can be measured or calculated, many conclusions may be drawn about, for example, pitch, timbre, intonation, utility of alternative fingerings and effects of bore shrinkage. Impedance measurement methods may sometimes be applied to instruments in museums, but are only meaningful if the instrument is in good playing condition, free from leaks. However, the overwhelming contribution to the acoustic properties of a woodwind is made by the shape of its air column. If the bore shape and tone holes are measured sufficiently accurately, we may compute the acoustic impedance of the instrument for all fingerings using standard equations of linear acoustics. This methodology has been thoroughly tested by applying it to a Heckel bass clarinet in A (German system) from 1910. This working instrument has been kept continuously in good playing condition but has seen relatively light use. Measurements were made using a calibrated tape measure and (plastic) Vernier calipers, which minimized bore damage. The results were compared with experimental measurement of acoustic impedances using a BIAS system at the Open University. Impedance calculation software was written in MatLab™ following the scheme of Plitnik and Strong , using the later developments by Keefe , Cronin and Dalmont et al. For all fingerings the impedance peaks agreed with the calculations, on average to better than 10 cents in frequency for the peak forming the basis of the sounding note. This could be empirically corrected by an end correction of 3 mm (on a 1350 mm instrument). The reed/embouchure impedance was semi-empirically corrected by an end correction of 17 mm, which is consistent with the theory and experiments of Dalmont et al.4 on soprano clarinets. Playing tests were in good agreement. The playing frequencies agreed well with the calculations using the above end corrections, both when the mouthpiece was fully pushed in and when it was pulled out by 10.8 mm to correct overall intonation. The calculations also correctly predicted the excellent tuning and timbre of the fork fingering for written Bb2, the “patent C#” fingering for C#3 and the unsuitability of the fork fingering for Eb2, which was about a quarter-tone sharp. The ‘impedance mapping’ method of Jeltsch et al. has been further developed into a powerful tool for summarizing the acoustical behavior of a complete instrument and comparing it with other instruments. A new method of determining the cut-off phenomenon in woodwind instruments, utilizing the higher resonances in the tube, has shown that there is a cut-off band rather than a single frequency. In the case of the Heckel, the Benade approximation gives a cut-off frequency of 1000 Hz, whereas there is actually a range of 920 - 1320 Hz, dependent on the fingering. These methods are being applied to the study of non-playable bass clarinets in museum collections, in an attempt to elucidate musical differences between instruments of different designs

Impact of Lake Nasser on the groundwater of the Nubia sandstone aquifer system in Tushka area, South Western Desert, Egypt

AbstractLake Nasser recharges the aquifers in study area by large amount of water increasing the groundwater level upward in the study area and decreasing groundwater salinity. The main result of the current study shows that the seepage water from Lake Nasser attains 24×106m3/year. Lake Nasser is located within the Abu Simbil and Sabaya Formations, which are characterized by a high hydraulic permeability and affected by E–W fault system. The groundwater is exploited from Abu Simbil and Sabaya sandstone aquifers. These aquifers exist under confined to unconfined conditions. The groundwater flows towards the north and northwest direction from Lake Nasser.The groundwater salinity increases towards the northwest direction coinciding with groundwater flow. This water salinity is probably decreased with time. This is mainly referred to the seepage of fresh water from Lake Nasser. The same hypothetical salts are detected in the water of Lake Nasser and the aquifers indicating that the groundwater in the study area is directly recharged from Lake Nasser

Hydraulic failure by heave and piping

It is generally agreed the same criterion for hydraulic heave and for piping can be used. In vertical upward flow the theory is well established. The weight of the soil must be greater than the seepage force of the water. Despite this well established theory piping and sand boiling occurs at much lower hydraulic gradient than the theoretical value. It is concluded that this discrepancy resulting from a conceptual error by not making distinction between the local and the global equilibrium. In the case of hydraulic heave the equilibrium of the entire soil prism (global equilibrium), while for the initiation of piping on the surface of the soil the equilibrium of one grain (local equilibrium) should be investigated. Investigating the local equilibrium of a single grain physical model for the initiation of piping is proposed. Criterion for piping on the top of a horizontal surface in granular soil subject to an upward flow deduced from first principles. It is concluded that hydraulic gradient alone does not sufficiently describe the hydraulic stability of the soil. The particle size and its distribution also have effect on the hydraulic stability of the soil. Critical grain diameter corresponding to the critical hydraulic gradient is introduced. If the diameters of the grains in a soil matrix are bigger than the critical diameter then the Terzaghi criterion is valid. Grains with smaller diameters lose their stability at lower hydraulic gradient than the critical one. The removals of grains from the soil matrix increase both the hydraulic gradient and the permeability of the soil. Thus the initial grain removal from the surface of the soil can progressively lead to sand boiling; therefore, the stronger criterion of piping should also be required for hydraulic heave

El penitente: una profesión trágica de la minería del carbón

Hubo una época en que la forma más habitual para evitar las explosiones de grisú y asfixias provocadas por este fluido gaseoso en las explotaciones de carbón era mediante el trabajo del penitente. En aquellos tiempos los tajos no eran muy grandes, se laboreaba en ellos de forma manual, y el gas generado no aparecía, por lo general, en gran cantidad. El penitente era una persona de experiencia que entraba en las minas antes de que los mineros llegasen a su trabajo, para explosionar los gases que allí existieran. Estaba cubierto con una especie de pasamontañas, guantes y capa, prendas realizados con tejidos gruesos o cuero, que eran humedecidas para protegerse del fuego. Iba arrastrándose sobre su vientre, mientras que con una larga pértiga, que portaba delante de él, llevaba una candela encendida en el extremo de la misma, para favorecer la explosión del grisú acumulado en el techo de las labores. Este personaje desaparecerá paulatinamente tras el invento de la lámpara de seguridad de Davy (1815). Aunque hay bastantes datos dispersos sobre esta profesión, en nuestro trabajo pretendemos abordar los siguientes aspectos: 1.-Cuándo y cómo aparece este personaje y hasta que época permanece en la minería. 2.- En que ámbitos geográficos se presenta y cuáles son sus diferentes denominaciones. 3.-Cuánto duraba su trabajo y cuál era su salario, en el caso de que lo tuviese. 4.-Cuál era su modus operandi. 5.-Cuáles y cómo son sus representaciones, indicando si es posible el nombre de los artistas que las hicieron. 6.-Cuál ha sido su presencia en la literatura. In a certain time, the most common way to avoid explosions and suffocation due to the presence of methane (fire damp) in coal mines was the labour of the fireman, also called penitent. As the coal beds were no so large, manual extraction were employed, and fire damp did not appeared in high amounts, but it was dangerous. The fireman was an experienced man who entered the mines before miners, in order to ascertain if gas exists and provoke the explosion of firedamp. He was covered by a mask, gloves and a cap, all of them made by thick textiles or leather, which were humidified to protect from fire. The fireman creep over his belly, and with the aid of a pole with a candle at its edge, to produce the explosion of fire damp. The work of fireman progressively disappeared after the discovery of the Davy´s lamp. Although there are some data about the existence of firemans, this paper deals with the following topics: 1.-When and how the fireman appeared and for how long was employed in coal mines. 2.- In which regions the fireman was employed, and which were the different names. 3.-Which was his workday and which was his salary. 4.- Which was his modus operandi. 5.-Which and how were the artistic representations, indicating, if possible, the name of the artists. 6.-Which was his presence in literatur

05-11-2016 SWOSU Students Named to Honor Rolls

A total of 1,321 students have been named to honor rolls at Southwestern Oklahoma State University for academic work during the 2016 spring semester on the Weatherford campus

12-22-2015 Nearly 1,300 Named to SWOSU Honor Rolls

Honor rolls at Southwestern Oklahoma State University in Weatherford and Sayre have been announced for the 2015 fall semester

Steampunk i romantyzm – Czterdzieści i cztery Krzysztofa Piskorskiego

The aim of the article is to read Krzysztof’s Piskorski novel Czterdzieści i cztery as a part of steampunk. In order to do so, we will trace the elements of this subgenre in the work and the method of implementation of its basic assumptions. In addition, the text aims at showing references to the romantic tradition that take place at various levels of the novel. Both planes are finally brought together. The whole makes it possible to see a combination of steampunk with the romantic tradition from both perspectives and to explore why this melange has brought the writer such reading success. Another relevant aspect of the research is embedding the work in the contexts of: fantasy literature, Maria Janion's romantic paradigm theory and popular culture.Zamiarem artykułu jest próba odczytania powieści Czterdzieści i cztery Krzysztofa Piskorskiego poprzez przyjrzenie się jej funkcjonowaniu w ramach steampunku. W tym celu prześledzone zostały występujące w utworze elementy tego podgatunku oraz sposób realizacji jego podstawowych założeń. Ponadto tekst skupia się na ukazaniu odwołań do tradycji romantycznej, jakie dokonują się na różnych poziomach powieści. Obie z wymienionych płaszczyzn zostają do siebie odniesione. Pozwala to ujrzeć obecne w Czterdzieści i cztery połączenie steampunku z tradycją romantyczną z obu perspektyw, a także zgłębić, dlaczego melanż ten przyniósł pisarzowi taki sukces czytelniczy. Istotne dla badań jest osadzenie utworu w kontekstach: literatury fantastycznej, teorii paradygmatu romantycznego Marii Janion oraz kultury popularnej