bluuebunny/crossref_metadata_2025_split huggingface dataset:
RANCANG BANGUN APLIKASI PEMBELAJARAN JARINGAN KOMPUTER UNTUK MENINGKATKAN PRESTASI AKADEMIK SISWA SEKOLAH MENENGAH KEJURUAN TEKNIK INFORMATIKA
Authors: Indrawati Indrawati 
Published: May 2019

Pergeseran paradigma proses pembelajaran konvensional ke media pembelajaran berbasis ICT telah berkembang dengan pesat. Pada penelitian ini, dirancang sebuah aplikasi alat bantu ajar yang bertujuan untuk meningkatkan prestasi akademik peserta didik pada sekolah kejuruan. Aplikasi soal dirancang menggunakan metode sampling random agar soal latihan dapat diacak. Hasil rancangan diuji dengan pengujian performansi dengan 20 responden guru dan pengujian implementasi dengan 24 responden siswa. Pengujian performansi memiliki akurasi dengan tingkat penilaian ”cukup” sebesar 7,5%, kategori ”baik” sebesar 62,50% dan kategori ”sangat baik” sebesar 30%. Pada pengujian implementasi ditemukan pengaruh yang signifikan antara penggunaan metode pembelajaran berbasis ICT dibanding metode pembelajaran konvensional dimana terjadi peningkatan yang signifikan siswa dengan prestasi ”kurang” dari 12,5% menjadi 0%, prestasi ”cukup” dari 50% menjadi 4,2%, demikian juga prestasi ”baik” meningkat dari 29,2% menjadi 62,5% dan prestasi ”sangat baik" meningkat dari 8,3% menjadi 33,3. Nilai t hitung sebesar -9.173, negatif mengindikasikan bahwa nilai siswa pada pembelajaran secara konvensional lebih rendah dibandingkan dengan pembelajaran secara ICT.Kata kunci: Jaringan Komputer, Simulasi, ICT, Interaktif
Pemberdayaan Masyarakat Desa Sumberdadi dengan Pelatihan Hidroponik dan Pupuk Organik
Authors: Nugraha Aldila Wanda 
Published: May 2019

Pertanian merupakan potensi yang ada di Desa Sumberdadi. Mitra sasaran di Desa Sumberdadi adalah warga usia produktif yang kurang memanfaatkan manajemen waktu dengan optimal. Pemberdayaan masyarakat di Desa Sumberdadi Kecamatan Sumbergempol Tulungagung ini dilatarbelakangi masalah warga usia kerja yaitu waktu luang yang kurang produktif, rendahnya pemanfaatan lahan pekarangan sempit di rumah waga mitra, pengetahuan yang rendah tentang pola tanam hidroponik, serta minimnya pengetahuan mitra sasaran tentang produksi pupuk organik. Pemberdayaan masyarakat ini bertujuan untuk meningkatkan ketrampilan, pengetahuan serta produktivitas produk hidroponik dan pupuk organik. Target luaran dalam kegiatan ini adalah (1) meningkatnya pengetahuan dan ketrampilan, kesadaran serta memotivasi mitra sasaran khususnya kelompok ibu-ibu dalam pemanfaatan lahan kosong/ pekarangan sebagai sumber pangan/ketahanan pangan dan sumber alternatif pendapatan keluarga; (2) instalasi teknik hidroponik sederhana dan pemeliharaannya yang dapat diterapkan oleh masyarakat; dan (3) mampu memproduksi pupuk organik untuk tanaman, khususnya hidroponik dan tanaman dengan metode konvensional lain. Metode partisipatif digunakan untuk melibatkan mitra secara aktif dalam pelaksanaan penerapan teknik hidroponik dan produksi pupuk organik. Hasil kegiatan yang sudah dilaksanakan antara lain, introduksi metode dan teknik instalasi hidroponik, pengetahuan alat dan bahan, dan cara produksi pupuk organik serta aplikasinya. Program pengabdian masyarakat yang sudah dilaksanakan ini membantu mitra sasaran dalam menyelesaikan permasalahan dan meningkatkan produktivitas mitra sasaran.
Analysis of a Helicopter Blade Fatigue Fracture by Digital Fractographic Imaging Analysis
Authors: McSwain R. H. , Gould R. W. 
Published: May 2019

Abstract
A helicopter was hovering approximately 10 ft above a ship when one spar section failed explosively. Visual inspection revealed a crack had progressed through one member of a dual spar plate assembly at a fold pin lug hole. The remaining spar plate carried the blade load until the aircraft was landed. The helicopter main rotor blade spar fracture was analyzed by conventional and advanced computerized fractographic techniques. Digital fractographic Imaging Analysis of theoretical and actual fracture surfaces was applied for automatic detection of fatigue striation spacing. The approach offered a means of quantification of fracture features, providing for objective fractography.
Airplane Fuel Line Support Bracket Failure
Authors: Hutchinson J.W. 
Published: May 2019

Abstract
A single-engine aircraft was climbing to 8000 ft when the engine suddenly lost power. The landing gear was torn off during the emergency landing. During the field investigation, the fuel line was found to be separated from the fuel pump outlet due to a failure of the elbow fitting. A bracket which supports the in-line fuel flow transducer also was found broken. Examination of the elbow fracture revealed characteristics of low-cycle fatigue failure. Examination of the support bracket fractures revealed a high-cycle mode of fatigue failure, with the primary fatigue extending along the full length of the 90 deg bend in the bracket. It was concluded that the failure was caused by an incorrectly-installed support bracket. It was recommended that the installation procedure be clarified.
In-Flight Separation of a Propeller in a Four Engine Aircraft
Authors: Hutchinson J.W. 
Published: May 2019

Abstract
A large four-engine aircraft was on a cargo flight at night when a loud bang was heard, accompanied by a loss of power from both engines on the left side. After an emergency landing, it was discovered that the propellers from both left side engines were missing. The initial investigation determined that the four-bladed propeller from the left inboard engine had separated in flight, subsequently impacting the left outboard engine, causing its propeller to separate also. Three years later, the left inboard propeller hub was recovered. All four blades had separated through the shank area adjacent to the hub. Detailed SEM examination confirmed a fatigue mode of failure in this area with a primary single origin on the inside surface of the shank. The main fatigue origin site was coincident with one of the defects on the inner surface of the blade shank. The most probable source for creating the defects on the ID bore of the shank was the blade tip chrome plating process, which was carried out during the last overhaul prior to the failure.
Damage Assessment in a Kevlar/Polyester Composite Component
Authors: Stumpff P.L. 
Published: May 2019

Abstract
The purpose of this investigation was to determine the cause of the ultrasonic signal attenuation noted during an inspection of a composite aircraft component. Although ultrasonics was able to identify the location of the defective areas, destructive analysis had to be utilized to determine the exact nature of the defect. The investigation describes how cross-sectioning, fractography, and chemical analysis were utilized to determine the type of defect responsible for the signal attenuation.
Use of Electron Fractography to Diagnose Hairline Cracking in an AISI 4340 Main Landing Gear Cylinder
Authors: Scott James A. 
Published: May 2019

Abstract
Ground maintenance personnel discovered hydraulic fluid leaking from two small cracks in a main landing gear cylinder made from AISI 4340 Cr-Mo-Ni alloy steel. Failure of the part had initiated on the ID of the cylinder. Numerous cracks were found under the chromium plate. A 6500x electron fractograph showed cracking was predominantly intergranular with hairline indications. Leaking had occurred only 43 h after overhaul of the part. Total service time on the part was 9488 h. It was concluded that cracking on the ID was caused by hydrogen embrittlement which occurred during or after overhaul. The specific source of hydrogen which produced failure was not ascertainable.
Use of Electron Fractography to Dianose Stress-Corrosion Cracking of an AISI 4340 Nose Landing Gear Cylinder
Authors: Scott James A. 
Published: May 2019

Abstract
A nose landing gear cylinder made from AISI 4340 Ni-Cr-Mo alloy steel was found cracked and leaking, causing partial depressurization. Investigation revealed the crack to be a stress-corrosion type, judging by the 6500x electron fractograph. It had started in a region of concentrated, large non-metallic inclusions near the chromium-plated ID of the cylinder. Also, there were breaks in the chromium plate and pits in the underlying base metal. The cylinder had been in service for 18,017 h, and 5948 h had passed since the first and only overhaul. Substandard plating of the ID at this time ultimately resulted in pitting of the metal. The combination of surface pitting and stress concentration at the nearby inclusions resulted in stress-corrosion cracking.
Uncommon Failures in Aluminum Alloys
Authors: Pellegrini H.V. , Bishop C.M. , Bennett J.M. 
Published: May 2019

Abstract
A longeron assembly constructed of Alclad 2024, some parts being in the T3 condition, others in the T42 condition, failed at a rivet hole. Plastic deformation at the crack site was found, but no plastic deformation was found in similar failed components. It was concluded that the numerous hairline cracks in the Alclad layer adjacent to the main fracture were fatigue cracks. In another case, bonded samples of 2024-T3 sheet were fatigue tested at various stress levels. Failures could be separated into three groups: those that failed in the adhesive bond, those that failed in the base material, and those that exhibited a dual failure. The last category failed in the adhesive bond and also showed a type of pitting on one face of the base material. In a third case, a 2024-T4 extrusion section was found to exhibit blistering after chemical milling. The presence of interconnecting microcracks between adjacent discontinuities supported a hydrogen blistering diagnosis.
Effects of Decarburization in Aircraft Components
Authors: Shah Jivan B. 
Published: May 2019

Abstract
A connecting rod from a failed engine ruptured in fatigue without evidence of excessive stresses, detonation, overheating, or oil starvation. The origin of the fatigue failure was completely mutilated but decarburization was observed. Significant amounts of decarburization (0.010 to 0.015 in.) were found also in other forgings, such as exhaust rocker arms, main rotor drag brace clevises, bolts of carriage diagonal struts, and spring legs of main landing gears. The failure mode was low-stress, high-cycle fatigue involving tension and bending loads. The main cause was a manufacturing deficiency. The usual way to eliminate decarburization is to machine off the soft skin or employ better quality control when making them. Many aircraft manufacturers employ forged parts with machined surfaces or with shot-peened as-forged surfaces without excessive decarburization.
Breakage of Main Undercarriage Axle of Landing Gear System of an Aircraft Under Simulated Testing
Authors: Das A. K. , Thippeswamy B. M. , Prasad J. 
Published: May 2019

Abstract
One main undercarriage axle made of high strength alloy steel was subjected to simulated fatigue test for 6000 h of service. After only 300 h it broke in two along the sharp radius. The fracture revealed a coarse, irregular, and brittle surface before final fracture by thick angular shear lip zone. The presence of micropores in the cleavage facets as well as at the grain boundaries and hairline type crack indications under SEM examination were all suggestive of hydrogen embrittlement. On the basis of investigation results and observations, it was concluded that the transverse breakage of the axle had occurred intergranularly in a brittle manner, possibly, initiated by a shallow zone of fatigue along the sharp radius acting as stress riser.
Analysis of Sub-Critical Cracking in a Ti-5Al-2.5Sn Liquid Hydrogen Control Valve
Authors: Meyn D. A. , Bayles R. A. 
Published: May 2019

Abstract
A liquid hydrogen main fuel control valve for a rocket engine failed by fracture of the Ti-5Al-2.5Sn body during the last of a series of static engine test firings. Fractographic, metallurgical, and stress analyses determined that a combination of fatigue and unexpected aqueous stress-corrosion cracking initiated and propagated the crack which caused failure. The failure analysis approach and its results are described to illustrate how fractography and fracture mechanics, together with a knowledge of the crack initiation and propagation mechanisms of the valve material under various stress states and environments, helped investigators to trace the cause of failure.
Effects of Prior Processing on the Service Life of an 18% Nickel Maraging Steel Helicopter Landing Mount
Authors: Pepi M.S. 
Published: May 2019

Abstract
The US Army Research Laboratory performed a failure investigation on a broken main landing gear mount from an AH-64 Apache attack helicopter. A component had failed in flight, and initially prevented the helicopter from safely landing. In order to avoid a catastrophe, the pilot had to perform a low hover maneuver to the maintenance facility, where ground crews assembled concrete blocks at the appropriate height to allow the aircraft to safely touch down. The failed part was fabricated from maraging 300 grade steel (2,068 MPa [300 ksi] ultimate tensile strength), and was subjected to visual inspection/light optical microscopy, metallography, electron microscopy, energy dispersive spectroscopy, chemical analysis, and mechanical testing. It was observed that the vacuum cadmium coating adjacent to the fracture plane had worn off and corroded in service, thus allowing pitting corrosion to occur. The failure was hydrogen-assisted and was attributed to stress corrosion cracking (SCC) and/or corrosion fatigue (CF). Contributing to the failure was the fact that the material grain size was approximately double the required size, most likely caused from higher than nominal temperatures during thermal treatment. These large grains offered less resistance to fatigue and SCC. In addition, evidence of titanium-carbo-nitrides was detected at the grain boundaries of this material that was prohibited according to the governing specification. This phase is formed at higher thermal treatment temperatures (consistent with the large grains) and tends to embrittle the alloy. It is possible that this phase may have contributed to the intergranular attack. Recommendations were offered with respect to the use of a dry film lubricant over the cadmium coated region, and the possibility of choosing an alternative material with a lower notch sensitivity. In addition, the temperature at which this alloy is treated must be monitored to prevent coarse grain growth. As a result of this investigation and in an effort to eliminate future failures, ARL assisted in developing a cadmium brush plating procedure, and qualified two Army maintenance facilities for field repair of these components.
Fretting and Corrosion in Aircraft Components
Authors: Shah Jivan B. 
Published: May 2019

Abstract
Fretting and/or fretting corrosion fatigue have been observed on such parts as main rotor counterweight tie rods, fixed-pitch propeller blades, propeller blade clamps, pressure regulator lines, and landing gear support brackets. Microcracks started from severe corrosion pits in a failed control rotor spar tube assembly made of cadmium-plated AISI 4130 Cr-Mo alloy steel. Inadequate design was responsible for the failure. A lower tine of the main rotor blade cuff failed in fatigue. The rotor blade cuff was forged of 2014-T6 aluminum alloy. Initial stages of crack growth displayed features typical of low stress intensity fatigue of aluminum alloys. The fatigue resulted from abnormal fretting owing to inadequate torquing of the main retention bolts. Aircraft maintenance engineers and owners were advised to adhere to specifications when torquing this joint.
Failure Analysis of a Cast Steel Crosshead
Authors: Chaudhari Mohan D. 
Published: May 2019

Abstract
A failed crosshead of an industrial compressor was examined using optical and SEM. The crosshead was an ASTM A148 grade 105-85 steel casting. On the basis of the observations reported and available background information, it was concluded that the failure began with the initiation of cracks at slag inclusions and sharp fillets in weld-repair areas in the casting. The weld-repair procedures were unsatisfactory. The cracks propagated in a fatigue mode. he casting quality was judged unacceptable because of the presence of excessive shrinkage porosity. It was recommended that crosshead castings be properly inspected before machining. Revision of foundry practice to reduce or eliminate porosity was also recommended.
Fracture of 99.90 Pure Tin Tubes
Authors: Dieser Karin 
Published: May 2019

Abstract
Some 99.90 pure tin tubes (0.15 mm thick) used for packaging a chemical compound cracked on bending and underwent brittle fracture prior to filling, while others remained ductile and showed no sign of failure. Examination showed that specimens prepared by mechanical methods such as electrolytic and hand polishing and the vibration method resulted in poor edge and crack edge definition due to material thickness. Etching experiments involved a grain surface attack and hence produced a rather strong surface relief from which the grain boundary cracks could again not clearly be differentiated. The sections were therefore examined unetched in polarized light. The microstructure of the cracked tubes was shown to have much smaller grains than the ductile and showed cracks from the surface down along the grain boundaries. Material hardness also differed between the unusable tubes and the ductile, and chemical analysis showed a higher level of aluminum in the brittle specimens. Failure obviously occurred due to the high material aluminum content that increased hardness which then caused embrittlement at the surface which led to cracks or fracture on bending. Since no explanation of how the aluminum entered the tin was available, no recommendations could be made.
Oxygen-Assisted Chloride Pitting of AISI 321 Stainless Steel
Authors: Kenny Philip J. 
Published: May 2019

Abstract
AISI type 321 stainless steel heat exchanger tubes failed after only three months of service. Macroscopic examination revealed that the leaks were the result of localized pitting attack originating at the water side surfaces of the tubes. Metallographic sections were prepared from both sets of tubes. Microscopic examination revealed that the pits had a small mouth with a large subsurface cavity which is typical of chloride pitting of austenitic stainless steel. However, no pitting was found in other areas of the system, where the chloride content of the process water was higher. This was attributed to the fact that they were downstream from a deaeration unit. It was concluded that the pitting was caused by a synergistic effect of chlorine and oxygen in the make-up water. Because it was not possible to install a deaeration unit upstream of the heat exchangers, it was recommended that a molybdenum-bearing stainless steel such as 316L or 317L be used instead of 321.
Failure Analysis of a Large Blender in a Chemical Plant
Authors: McCowan C.N. , Siewert T.A. 
Published: May 2019

Abstract
On 21 April 1995, the contents of a large blender (6 cu m) reacted and caused an explosion that killed and injured a number of workers at a plant in Lodi, NJ. A mixture of sodium hydrosulfite and aluminum powder was being mixed at the time of the accident. This report focuses on evaluations of the blender to determine if material or mechanical failures were the cause of the accident. The results indicate that the mixing vessel was metallurgically sound and did not contribute to the initiation of the failure. However, the vessel was not designed for mixing chemicals that must be isolated from water and excessive heat. Water leaking into the vessel through a graphite seal may have initiated the reactions that caused the accident.
Cavitation Erosion of a Zirconium Pump Impeller in an Aqueous Hydrochloric Acid Service Environment
Authors: Parrington R.J. 
Published: May 2019

Abstract
Post-service destructive evaluation was performed on two commercially pure zirconium pump impellers. One impeller failed after short service in an aqueous hydrochloric acid environment. Its exposed surfaces are bright and shiny, covered with pockmarks, and peppered with pitting. Uniform corrosion is evident and two deep linear defects are present on impeller blade tips. In contrast, the undamaged impeller surfaces are covered with a dark oxide film. This and many other impellers in seemingly identical service conditions survive long lives with little or no apparent damage. No material or manufacturing defects were found to explain the different service performance of the two impellers. Microstructure, microhardness and material chemistry are consistent with the specified material. Examination reveals the damage mechanism to be corrosion-enhanced cavitation erosion, the most severe form of erosion corrosion. Cavitation damage to the protective oxide film caused the zirconium to lose its normally outstanding corrosion resistance. The root cause of the impeller failure is most likely the introduction of excessive air into the pump due to low liquid level, a bad seal or inadequate head. Corrosion pitting, crevice corrosion, and solidification cracks (casting defect) also contributed to the failure.
Creep Damage in Welds of Reformer Furnace Tubing
Authors: da Silveira T.L. , Le May I. 
Published: May 2019

Abstract
A sample tube was removed from a reformer furnace for life assessment after 69,000 h of service. Sections were cut from the tube, which was a spindle cast A297 Grade HK 40 (25 Cr, 20 Ni, 0.4 C) austenitic steel of 122.5 mm OD and 10.5 mm nominal wall thickness. They were examined metallographically on transverse sections and on longitudinal sections through the butt welds joining the separate cast segments of the tube. Creep damage was mainly concentrated within the inner one third of the wall thickness. The use of damage assessment parameters in evaluating the reformer tube remaining life showed the welds to be inadequate, and to have a strength and creep resistance below those of the base metal.
Failure of Supports in a Petrochemical Product Transfer Line
Authors: da Silveira T.L. , Le May I. 
Published: May 2019

Abstract
Leakage was detected at the welds between stiffening plates and the pipe in a transfer line carrying butane and related petrochemical compounds. The line and reinforcing rings were of AISI 316 stainless steel, the pipe being of 508 mm diam and 6.25 mm wall thickness. The design temperature and pressure were 621 deg C and 2.75 kPa, respectively, while the operating conditions were 579 deg C and 1.03 kPa. The line was insulated. Failure occurred after approximately 90,000 h of operation, shutdowns being approximately two per annum. The cracking occurred at the toe of welds between the plates and the pipe. The creep damage failure was attributed to repeated relaxation cycles of very high thermal stresses of resulting from the periodic shutdowns, temperature fluctuations during service, or both. This failure emphasized the information available from an evaluation of the operative creep mechanism, namely grain boundary sliding, relating to the periodic nature of the loading, with high residual stresses being present.
Fracture of a Lifting Fork Arm
Authors: Paul Günter 
Published: May 2019

Abstract
A forged alloy steel arm of a lifting fork with an approximate cross section of 150 x 240 mm (5.92 x 9.45 in.) fractured after only a short service life on a lift truck. The fracture surface had the appearance of a fracture originating from a surface crack. Analysis (visual inspection, 200x micrographs, chemical analysis, and metallographic examination) supported the conclusion that the primary cause of the failure was the brittleness (lack of impact toughness) of the steel. The coarse bainitic microstructure was inadequate for the service application. The microstructure resulted from either improper heat treatment or no heat treatment after the forging operation. The surface cracks in the lifting-fork arm acted as starter notches (stress raisers), assisting in the initiation of fracture. No recommendations were made.