Advances in Electron Beam Melting of Aluminum Alloys

The high thermal conductivity and melt pool optical reflectivity associated with aluminum alloys can pose significant challenges for direct-metal SFF processes. The use of SFF processes to produce aluminum parts is often not cost effective relative to CNC machining for simple geometries. However, the use of SFF techniques for aluminum alloys is justified for some applications such as aerospace forgings or high surface area heat exchangers. This paper describes recent progress in processing aluminum alloys using the Electron Beam Melting process. Structure and properties will be discussed, as well challenges associated with high vapor pressure alloying elements such as zinc and magnesium.Mechanical Engineerin

You Will Never See Any God

A farmer perishing under a fallen tractor makes a last stab at philosophizing: “There was nothing dead that was ever beautiful.” It is a sentiment belied not only by the strange beauty in his story but also in the rough lives and deaths, small and large, that fill these haunting tales. Pulp-fiction grim and gritty but with the rhythm and resonance of classic folklore, these stories take place in a world of shadowy figures and childhood fears, in a countryside peopled by witches and skinflints, by men and women mercilessly unforgiving of one another’s trespasses, and in nights prowled by wolves and scrutinized by an “agonized and lamenting” moon. Ervin D. Krause’s characters pontificate in saloons, condemning the morals of others as they slowly get sloshed; they have affairs in old cars on winter nights; they traffic in gossip, terrorize their neighbors, steal, hunt, and spy. This collection includes award-winning stories like “The Snake” and “The Quick and the Dead” as well as the previously unpublished “Anniversary,” which stirred a national controversy when it was censored by the University of Nebraska and barred from appearing in Prairie Schooner. Krause’s portrayal of the matter-of-fact cruelty and hopeful fragility of humanity is a critical addition to the canon of twentieth-century American literatur

Kompresi Data Teks Menggunakan Pendekatan Grammar Compression Dengan Algoritma Sequ Itur

Ukuran media penyimpanan data yang terbatas dan kebutuhan waktu transfer datayang cepat merupakan suitu masalah yang dihadapi dalam menyimpan dan mentransfer data.Sequitur merupakan algoritma kompresi yang dapat menyimpulkan konteks tatabahasa apa saja. Sequitur merniliki 2 batasan dalam memampatkan data teks yaittt digramuniqueneis danrule utility, dimana 2 batasan ini akan diterapkan dalamprogramkompresi yangakan dibangun ini. Melalui penelitian dan analisis yang dilakukan pada karya tulis ini diperolehbahwa semakin besar file yang akan dimampatkan dengan besarnya compressed charactersbase yang digunakan maka peluang keberhasilan pemampatan data teks juga sernakin besartetapi membutuhkan waktu yang cukup lama dalampemampatan tersebut

Patterns of Genetic Diversity in Highly Invasive Species: Cogongrass \u3ci\u3e(Imperata cylindrica)\u3c/i\u3e Expansion in the Invaded Range of the Southern United States (US)

The spatial expansions of invasive organisms in the novel range are generally expected to follow an isolation-by-distance relationship (IBD) if the invasion is biologically driven; however, many invasions are facilitated anthropogenically. This research focused on the extant expansion patterns of cogongrass (Imperata cylindrica). Cogongrass is a widespread invasive species throughout the southern United States (US). Patterns of infestation vary among US states. Cogongrass is pyrogenic, and its invasion threatens softwood (Pinus spp.) plantations, a substantial economic market for this US region. Over 600 individuals were sampled from seven invaded US states, using amplified fragment length polymorphisms (AFLPs) to assess genetic diversity and population structure. We suspected that differences in historical management efforts among US states influenced differences in genetic diversity and structure. We detected two genetic lineages at the highest level of analysis. One genetic lineage was locally restricted, whereas the other was found throughout the study region. Admixed individuals were found in all US states and consistently co-occurred with the dominant lineage, suggesting that secondary contact and hybridization may have facilitated expansion. The widespread prevalence of only one of the two detected genetic lineages suggests a primary genetic lineage responsible for on-going population expansion in the US

Land-use controls for outdoor recreation areas

Land-use planning and control is fast becoming a major issue in the United States. Dwindling natural resources, a growing population, a recognized need for a quality environment, and several incidents of controversial resource management have brought land-use problems to the public eye. State land-use legislation, numerous court cases, and extensive debate have resulted. Central to the general debate is concern over the role of government in this area, formerly considered to be the realm of the individual and private firm. This paper is designed to help clarify the role of government in land-use planning and control by analyzing the powers available to government entities in providing opportunities for outdoor recreation.https://lib.dr.iastate.edu/specialreports/1074/thumbnail.jp

Conservation tillage : costs and returns (1993)

This publication briefly describes tillage systems and estimates costs and returns on a typical farm.Reviewed October 1, 1993