Figure de Chladni

Les nœuds de vibration d’une plaque élastique mince dessinent des lignes caractéristiques de la fréquence propre excitée. La matérialisation de ces lignes avec une poudre, généralement de la poudre de lycopode, forme les figures dites de Chladni.

Sur un support central sont fixées de manière rigide différentes plaques métalliques horizontales de taille, de forme et d’épaisseur différentes. Contrairement à la partie centrale fixe, la périphérie de ces plaques n’est pas assujettie au support. Elle est donc libre de vibrer.

Une fois la plaque fixée au support best vacuum thermos, on dispose du sable sur celle-ci puis on la met en vibration, par exemple grâce à un archet que l’on frotte verticalement sur le bord de la plaque. Sous l’excitation de l’archet, la plaque vibre, le sable se déplace depuis les zones de forte vibration vers les zones où la vibration est moins forte voire nulle (nœuds de vibration de l’onde stationnaire) formant ainsi des figures de Chladni running water belt reviews.

En étudiant une même plaque, la modification de la position du point d’excitation fait apparaitre des figures différentes qui correspondent aux différents modes vibratoires de cette plaque. On peut également atténuer la vibration à certains endroits en y posant un doigt. D’autres figures apparaissent lorsqu’on modifie les paramètres (forme de la plaque, taille, épaisseur, etc.).

Les figures de Chladni peuvent être aussi utilisée en facture instrumentale pour contrôler la qualité ou l’acoustique d’un instrument.


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Goffertpark

The Goffertpark is a public park in Nijmegen, The Netherlands. In the park, which is sometimes used as an outdoor concert venue, there’s also the stadium of football club N.E.C..

Sixty acres of woodland and heathland changed in the thirties by the effort of Nijmegen unemployed in a spacious park, including provision of sports fields, a stadium, a teahouse and a zoo. The new Goffertpark went on Saturday best vacuum thermos, July 8, 1939 open to the public.

Like many other Dutch municipalities Nijmegen in the thirties was hit hard by the global economic crisis. The number of unemployed went up to 29 percent now, the downtown became even more than half of workers without work. The support costs rose alarmingly. Through major projects in road construction waterof, dike reinforcements or park the Empire tried to keep people at work. Often it was to heavy physical work, for which more than seventy percent of the normal salary received. Thus were unemployed Nijmegen already used in the construction of the Maas-Waal canal and the construction of the Waal bridge.

The plans for the Goffertpark were part of the General Expansion of Nijmegen, prepared by planning early thirties A. Siebers. This expansion included a network of ring roads and radials, following the canals around the old town. Districts should be provided with green strips, parks and playgrounds seasoned meat tenderizer. And in the southwest of the city would be around the old farm Goffert The Volkspark come for a great recreational and sporting activities. Elsewhere in the Netherlands when these parks were built, such as the Hague and Amsterdam Forest Zuiderpark. On the insistence of Mayor J. A.H. Steinweg took the Empire in the context of the construction costs of unemployment relief Goffertpark itself. From the spring of 1935 there were over 160 unemployed people to work for a fee of 35 cents per hour. Although the construction of the park was used the natural slope of land, were still 600,000 cubic metres of sand are moved. For as many people into work, but this did not happen with excavators with shovels and wheelbarrows. By far the hardest job was digging the six metres deep pit for the stadium, which it nicknamed “the bloedkuul” remained. The park has been throughout the years a venue for public events in Nijmegen and in recent years also for concerts.

The park is inscribed as a municipal monument.

The stadium, with athletics and cycling, became the home of football in 1939, when N.E.C. moved there. Over the years, there were various events and performances. In 1999, sixty years after the opening, park and stadium were thoroughly refurbished and modernized.

Artists, including AC/DC, Aerosmith, Iron Maiden, Black Sabbath, Bon Jovi, Bruce Springsteen and the E Street Band, Coldplay, Deftones, Guns N’ Roses, Kings of Leon, KISS, Korn, Limp Bizkit, Linkin Park, Metallica, Mudvayne, Muse, Pearl Jam, Pink Floyd, R.E.M., Radiohead, Red Hot Chili Peppers, The Rolling Stones, U2, Van Halen, and Velvet Revolver have performed at the Goffertpark as a concert venue.

Coordinates:


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Godfried van Voorst tot Voorst

Battle of the Netherlands

Jan Joseph Godfried, Baron van Voorst tot Voorst (Godfried) Jr. (December 29, 1880, Kampen –November 11, 1963, Vierakker) was the second highest officer in command of the Dutch armed forces during World War II and a renowned strategist, who wrote numerous articles and books on modern warfare.

He was the fifth child of Jan Joseph Godfried van Voorst tot Voorst sr. (1846–1931), lieutenant general and president of the Senate, and Anna Cremers (1851–1933). With his first wife, Jkvr. Octavia Ottine van Nispen tot Pannerden (1885–1947), he had 6 children. His second wife, Jkvr. Joanna Maria Alfrida Louisa (1910–1992), was a daughter of the Dutch Prime Minister Charles Ruijs de Beerenbrouck best vacuum thermos.

After he completed his secondary education, he was admitted to the Royal Military Academy (KMA) in Breda in 1898. In 1901, he graduated first in his class, and enlisted in an infantry regiment in Haarlem. During the general railway strikes in 1903, he was the only lieutenant in charge of a unit protecting the train station of Haarlem. In 1907, he became a personal adjutant of Queen Wilhelmina, and in this function accompanied her on various state visits. During the First World War and the mobilization of the Dutch Army, he served in various ranks. These experiences and his concerns regarding the Schlieffen Plan led him to write a study highlighting the critical importance of the province of Limburg in German strategic planning. The publication was translated into Spanish, English, French and Norwegian. In 1920, Godfried became a member of the general staff and represented the Netherlands in the disarmament conference in Geneva.

In the wake of the Great Depression steel insulated water bottle, he managed to restore order after the 1934 riots in Amsterdam. This was the first time that armored vehicles were deployed by the Dutch army. In 1935, he supervised the Dutch troops monitoring the 1935 plebiscite in the Saar.

Throughout the 1920s and 1930s, he was highly critical of the “broken rifle” movement and the prevailing pacifist mentality of Dutch society and politics, which he deemed naïve. In later life, he would comment that this era was the low point in the history of Dutch defense. In 1936, he published a widely read book on the German rearmament —an early warning against Nazi militarism.

By the late 1930s, Dutch politicians finally realized that their country would not be able to remain neutral in the looming conflict with Nazi Germany. During the hasty and belated military preparations, Godfried firmly rejected the ideas of general Izaak Reijnders. Godfried warned against Blitzkrieg tactics and mechanized warfare, whereas Reijnders believed that a possible German invasion would be preceded by long political and diplomatic tensions. Although, Reinders’s plans were initially adopted, his conflict with the secretary of defense Adriaan Dijxhoorn led to the resignation of the former. Since two brothers of the van Voorst tot Voorst family served in the general staff and because their catholic background was controversial among Protestants, Dijxhoorn appointed the retired general Henri Winkelman, who supported the strategic plans of Godfried.

Much time was lost due to these internal arguments, and when Nazi Germany invaded the Netherlands on May 10, 1940, the Dutch armed forces were insufficiently prepared. Godfried attempted to defend the Grebbeberg, but was ultimately forced to withdraw to the West of the Netherlands. After the Rotterdam Blitz and the German threat to annihilate other Dutch cities electric pill remover, he advised Winkelman to surrender.

After the Battle of the Netherlands, he refused to pledge an oath of loyalty to the Nazis, and as a consequence, he was sent (together with his brother, H.F.M. baron van Voorst tot Voorst) to a prisoner-of-war camp in Germany for the 5 remaining years of the war. Following the end of Nazi Germany, he returned to the Netherlands, where he assumed various military and civil positions. In 1960, on his 80th birthday, he was awarded the titular rank of general.


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