bluuebunny/crossref_metadata_2025 huggingface dataset:
ANÁLISE MICROESTRUTURAL DO AÇO 1018 APÓS ENSAIO DE CORROSÃO
Authors: Nogueira Arthur De Sousa Gomes , Rangel Ygor Peixoto , Oliveira Thais Dos Santos , E Silva Geanni Barbosa da Silveira
Published: October 2017

RESUMO  É indiscutível a aplicabilidade dos materiais metálicos na indústria. O bom emprego de determinados materiais dependem diretamente do meio onde serão utilizados, das propriedades necessárias, custo-benefício, entre outros fatores. Dentre os aços mais comumente utilizados, destaca-se o aço 1018. Os aços de baixo teor de carbono são relativamente fáceis de serem usinados em qualquer modelo de máquina, além de poderem ser conformados facilmente. Porém, os mesmos não apresentam resistência à corrosão, que é um fator imprescindível para que as propriedades e vida útil sejam mantidas. A cada dia as empresas visam minimizar os custos que envolvem a corrosão, sendo assim, necessitam cada vez mais aprimorar os conhecimentos sobre esse assunto tão relevante. Para que isso ocorra há uma crescente perspectiva no desenvolvimento de técnicas, análises, assim como métodos preventivos. Através desse trabalho foi possível acompanhar o comportamento do aço 1018 após ensaio de corrosão e identificar da morfologia obtida. Esperava-se um acometimento localizado maior, porém a corrosão generalizada foi a predominante, sendo classificada como severa, segundo a norma NACE Standard RP0775 (2005).  Esses resultados foram alcançados através de análises, ensaios e caracterizações através de normas. Palavras-chave: Aço carbono; Corrosão; Ensaios; Caracterização.
Requisitos do Projeto Elétrico de Motores de Indução para Acionamento por Variador de Velocidade
Authors: Gonçalves Henrique
Published: October 2017

O acionamento de motores elétricos de indução por inversores estáticos de frequência (comercialmente denominados variadores de velocidade) é uma solução já amplamente utilizada na indústria. Contudo sendo, há ainda muito para ser, feito, estudado e compreendido principalmente ao nível da interação entre o variador e o motor, para que tais aplicações sejam efetivamente vantajosas em termos de eficiência energética e atrativas em termos de custo. Neste artigo são expostos os principais desafios que são colocados aos fabricantes de motores e que resultam da alimentação dos mesmos por uma fonte de tensão PWM com elevadas frequências de comutação. São apresentadas algumas considerações normativas e apresentadas algumas soluções comummente utilizadas para mitigar os problemas sentidos.
Types and Construction of Power Transformers
Authors: Bolotinha Manuel
Published: October 2017

Transformers may be classified according to dielectric insulation material as follows: • Oil-filled transformers• Dry type transformers
Previsão do Diagrama de Carga de Subestações da REN Utilizando Redes Neuronais
Authors: Rocha Silvana Mafalda , Costa Maria Teresa , Gonçalves Manuel João
Published: October 2017

A previsão de diagramas de carga é bastante utilizada por diversas empresas que lidam com o setor elétrico, o que torna este processo muito importante para a eficiência e qualidade. As Redes Neuronais Artificias (RNA) são uma técnica computacional com diversas áreas de aplicação, sendo uma delas a previsão de cargas.Ao longo deste artigo está presente todo o processo realizado para alcançar as redes ideais de duas subestações da Rede Elétrica Nacional (REN), Prelada e Ermesinde, e posteriormente desenvolver um método de previsão eficaz para diagramas de carga e comprovar que a utilização de RNA são uma mais-valia no alcance de boas previsões.
Interruptores (Mecânicos) Para Instalações Elétricas Fixas, Domésticas e Análogas
Authors: Gomes António Augusto Araújo
Published: October 2017

Um interruptor (mecânico) é definido como um aparelho mecânico de conexão capaz de estabelecer, de suportar e de interromper correntes nas condições normais do circuito, incluindo, eventualmente, as condições especificadas de sobrecarga em serviço.É um aparelho que é ainda capaz de suportar, num tempo especificado, correntes nas condições anormais especificadas para o circuito, tais como as resultantes de um curto-circuito.Pode ser capaz de estabelecer correntes de curto-circuito mas não de as interromper.
ITED 3 – Dimensionamento das Redes de Cabos Coaxiais
Authors: Pinho José Eduardo , Silva Marco Rios da , Ramos Sérgio Filipe
Published: October 2017

Em Setembro de 2014 foi editada a 3ª Edição do Manual das Infraestruturas de Telecomunicações em edifícios (ITED), que veio responder à necessidade de uma atualização técnica, bem como dar resposta à questão do paradigma do setor imobiliário.Essa 3ª Edição apresentou algumas alterações face à edição anterior, designadamente no que toca ao dimensionamento de redes de cabos coaxiais (CC).Com este artigo, pretende-se apresentar as alterações mais significativas entre a 2ª e 3ª Edição do Manual ITED, nomeadamente no que toca ao dimensionamento de redes de cabos coaxiais.Pretende-se, também, apresentar uma aplicação informática que foi desenvolvida no âmbito do curso da Licenciatura em Engenharia Eletrotécnica – Sistemas Elétricos de Energia, evidenciando os vários aspetos no domínio do dimensionamento de redes coaxiais em redes coletivas e individuais.Por fim, apresenta-se um caso de estudo, que pretende ao mesmo tempo demonstrar a forma como a aplicação informática funciona, bem como a sua fiabilidade.
ITUR 2 – Dimensionamento das Redes de Cabos Coaxiais
Authors: Vieira Sérgio Manuel Correia , Silva Marco Rios da , Ramos Sérgio Filipe
Published: October 2017

No último século, o sector das comunicações passou de um estado inicial de simples curiosidade tecnológica até um dos mais dinâmicos pilares económicos de vários países por todo o mundo.
NFPA 850:Firetrace e os Fogos em Turbinas de Vento
Authors: Neves Carlos
Published: October 2017

As Turbinas de Vento ou Aerogeradores podem Atingir 90 metros de altura e custar mais de 1 milhão de euros.As condições críticas do seu funcionamento, como o ambiente atmosférico com ventos fortes e relâmpagos; as vibrações; as poeiras; as grandes alturas e o difícil acesso para manutenção, tornam a ocorrência de incêndio muito provável.O que será melhor, ver pacientemente um fogo destruir até à exaustão a turbina ou, ter instalado um sistema que o elimina logo na origem?
Smart Panel
Authors: Carvalho Luís , Vaz Paulo
Published: October 2017

Na sociedade atual, a preocupação com o ambiente, por um lado, e com o conforto e a segurança, por outro, faz com que a sustentabilidade energética se assuma como uma forma de intervenção adequada às exigências de qualidade de vida e à eficiência no âmbito da economia. Nesta conformidade, é incontornável a mais-valia do Smart Panel, um quadro elétrico inteligente criado pela Schneider-Electric com vista à consecução daqueles desideratos.Iremos abordar, neste artigo, a gama de produtos que perfazem esta tecnologia, fazendo uma breve descrição de cada um deles, expondo de seguida um exemplo de aplicação desta tecnologia. Numa fase posterior apresentaremos as vantagens do Smart Panel face à tecnologia tradicional (até hoje a mais comum) no que respeita ao controlo de um quadro elétrico, Sistema de Gestão Técnica Centralizada.
PM Motors for High Efficiency Applications
Authors: Martins Carlos Eduardo G. , Nau Sebastião Lauro
Published: October 2017

PM motors are suitable for nearly all applications, like pumps, elevators, compressors, blowers, extruders, generators, electric vehicles, servodrives, cooling towers, household appliances, etc. This paper will present some applications where the use of PM motors allowed for enhancements in energy efficiency and process quality.
Cable Laying and Pulling
Authors: Bolotinha Manuel
Published: October 2017

The common methods of cable laying are: • Direct in the ground in trenches (underground cables).• In cable trenches in outdoors switchyards.• In cable trays or cable ducts• Fixed with clamps (usually at walls and ceilings).• In conduits.
Ground Fault Protection methods for Distribution Systems
Authors: Tavares Hugo Ricardo dos Santos , Nogueira Teresa Alexandre
Published: October 2017

The system grounding method option has a direct influence on the overall performance of the entire medium voltage network as well as on the ground fault current magnitude. For any kind of grounding systems: ungrounded system, solidly and low impedance grounded and resonant grounded, we can find advantages and disadvantages. A thorough study is necessary to choose the most appropriate grounding protection system. The power distribution utilities justify their choices based on economic and technical criteria, according to the specific characteristics of each distribution network. In this paper we present a medium voltage Portuguese substation case study and a study of neutral system with Petersen coil, isolated neutral and impedance grounded.
ITED 3 – TILT O Que é e Como Se Ensaia!
Authors: Martins Hélder Nelson Moreira
Published: October 2017

O presente artigo aborda a problemática do TILT, os seja a diferença de atenuação/potência de sinal num dado ponto da rede de cabo coaxial, decorrente da 3ª Edição do Manual ITED e presentemente em vigor para projetistas, instaladores e fabricantes de equipamento eletrónico deste setor das comunicações eletrónicas.
Study Of Led Lamps Technologies Impact On The Utility
Authors: Szwal Ewelina , Puga José Teixeira , Ferreira Maria Judite , Gomes António Augusto Araújo
Published: October 2017

With the growing interest in the issue of reducing power consumption in electricity applications, energy-saving devises and the problem of their operation gains more attention. The increase in the utilization of energy-saving lamps, especially LED lamps, leads to the wide interest in their influence on the power system. The impact of discussed devices on the voltage and current in the grid must be thoroughly studied before launching devices into the market. The studies undertaken on the LED lamps present in a wide range the issue of harmonic emission from lamps and their influence on power quality. Due to many manufacturing technologies, different LED devices can have various effects on the utility. It is significant to carry out researches concerning the adverse effects of energy-saving lamps in order to utilize devices that meet certain requirements which are set by the international commissions.
PENERAPAN MODEL PEMBELAJARAN KOOPERATIF DENGAN METODE PENEMUAN TERBIMBING BERBANTU LKS PADA MATERI GEOMETRI DI KELAS III SEKOLAH DASAR NEGERI 2 KOTA BIMA
Authors: Hadi Arnasari Medekawati
Published: October 2017

Salah satu bagian dari materi matematika yang dapat mengembangkan kemampuan siswa dalam berpikir logis dan mengembangkan kreativitas siswa adalah materi geometri dengan pokok bahasan bangun datar. Pokok bahasan ini dapat dikategorikan kepada materi yang cukup sukar serta memerlukan pemahaman yang cukup tinggi. Sehingga, dalam mengajarkan materi geometri di SD, seorang guru harus dapat menyajikan materi awal secara konkrit, dan menghubungkan pembelajaran geometri dengan benda-benda nyata sehingga siswa dapat memahami materi dengan mudah. Kenyataan yang terjadi di lapangan khususnya di SD Negeri 2 Kota Bima, pada saat pembelajaran kebanyakan siswa hanya menerima dan menghafal konsep-konsep dan rumus-rumus yang diajarkan, tanpa tahu bagaimana proses penemuan konsep dan rumus dari materi tersebut. Hal itu menyebabkan siswa kurang paham terhadap konsep materi pokok geometri dan mengakibatkan kebanyakan siswa memperoleh nilai dibawah KKM yaitu 60. Salah satu variasi model pembelajaran yang dapat digunakan dalam proses pembelajaran adalah model pembelajaran kooperatif dengan metode penemuan terbimbing berbantu LKS.  Tujuan dari penelitian ini adalah untuk meningkatkan hasil belajar siswa pada materi geometri menggunakan metode penemuan terbimbing berbantu LKS. Metode yang digunakan dalam pengambilan data adalah lembar observasi siswa dan tes uraian. Hasil penelitian menunjukkan bahwa terjadi peningkatan aktivitas siswa dari 8 aktivitas menjadi 10 jenis aktivitas siswa berada dalam batas toleransi waktu yang diberikan dan dikatakan efektif. Sedangkan untuk hasil belajar diperoleh data bahwa siswa yang tuntas sebanyak 31 orang, siswa yang tidak tuntas sebanyak 5 orang, dan yang tidak mengikuti tes sebanyak 4 orang. Berdasarkan hasil tersebut, presentase ketuntasan belajar klasikal adalah 86,11%, karena terdapat lebih dari 85% dari jumlah siswa di kelas yang mencapai ketuntasan belajar, maka dikatakan bahwa siswa telah tuntas secara klasikal.Kata kunci: Penemuan Terbimbing, Lembar Kerja Siswa, Geometri
PENGARUH PENERAPAN KOMPETENSI PEDAGOGIK GURU DALAM PEMBELAJARAN MATEMATIKA BERBASIS KURIKULUM 2013 TERHADAP PRESTASI BELAJAR MATEMATIKA PESERTA DIDIK TAHUN PELAJARAN 2016/2017
Authors: Falachi Hawin , Kartana Tri Jaka , Utami Wikan Budi
Published: October 2017

Keberhasilan dunia pendidikan dipengaruhi oleh beberapa komponen, diantaranya guru, sarana dan prasarana serta lingkungan belajar yang efektif dan menyenangkan. Guru sebagai salah satu komponen di dalamnya memiliki tugas dan tanggung jawab yang besar. Terealisasinya proses belajar  mengajar yang optimal menggunakan kurikulum 2013, guru harus mampu mengembangkan rencana pembelajaran yang sesuai dengan kurikulum 2013. Oleh karena itu, sebagai guru persiapan secara matang harus dituangkan dalam merencanakan, melaksanakan, dan mengevaluasikan kegiatan belajar mengajar. Guru yang profesional harus memiliki kompetensi dalam melaksanakan program pembelajaran. Salah satu kompetensi yang harus dimiliki guru adalah kompetensi pedagogik. Tujuan penelitian ini adalah untuk mengetahui adanya pengaruh penerapan kompetensi pedagogik guru dalam pembelajaran matematika berbasis kurikulum 2013 terhadap prestasi belajar matematika peserta didik. Populasi dalam penelitian ini adalah seluruh peserta didik kelas VIII SMP Negeri se-Kota Tegal tahun pelajaran 2016/2017 yang telah menerapkan kurikulum 2013 yang terdiri dari 6 SMP dengan jumlah kelas sebanyak 45 kelas dan sebanyak 1.354 peserta didik. Pengambilan sampel menggunakan teknik cluster random sampling. Dengan menggunakan rumus formula empiris jumlah sampel yang digunakan sebesar 302 responden yang terbagi dalam 10 kelas. Metode pengumpulan data yang digunakan adalah angket dan dokumentasi. Teknik analisis data menggunakan uji regresi linear sederhana. Hasil penelitian ini menunjukkan bahwa, ada  pengaruh penerapan kompetensi pedagogik guru dalam pembelajaran matematika berbasis kurikulum 2013 terhadap prestasi belajar matematika peserta didik dengan tingkat pengaruhnya sebesar 20,69%. Kata Kunci: kompetensi pedagogik guru, pembelajaran matematika, kurikulum 2013, prestasi belajar.
Analisis Hambatan Belajar (Learning Obstacle) Siswa SMP Pada Materi Statistika
Authors: Yusuf Yusfita , Titat Neneng , Yuliawati Tuti
Published: October 2017

Pembelajaran statistika di SMP yang berlangsung selama ini tidak memperhatikan hambatan belajar  (learning obstacle) yang siswa alami, pada umumnya guru menyampaikan materi mengacu pada dokumen bahan ajar berupa buku paket atau buku-buku referensi. Oleh karena itu penting dilakukan sebuah penelitian yang mengkaji tentang hambatan belajar (learning obstacle) pada materi statistika SMP. Pembelajaran yang dirancang berdasarkan hambatan belajar (learning obstacle) akan menciptakan proses pembelajaran yang optimal.  Adapun tujuan dari penelitian ini adalah  menganalisis hambatan belajar yang terkait dengan materi statistika SMP dan faktor-faktor penyebabnya. Metode yang digunakan dalam penelitian ini menggunakan metode kualitatif. Berdasarkan hasil penelitian, diperoleh kesimpulan tersebut sebagai berikut. Siswa pada tingkat rendah mengalami kesulitan yang lebih besar dari pada siswa pada tingkat tinggi hampir pada setiap indikator.  Dalam pembelajaran statistika siswa mengalami ontogenic obstacle, epistemological obstacle dan didactical obstacle hal ini terlihat dari hasil tes, wawancara dan studi dokumen yang dilakukan oleh peneliti.Kata kunci: learning obstacle, ontogenic obstacle, epistemological obstacle, didactical obstacle, statistika.
ANALISIS KETRAMPILAN BERFIKIR KRITIS DALAM MEMECAHKAN MASALAH DITINJAU PERBEDAAN GENDER
Authors: Cahyono Budi
Published: October 2017

Tujuan dari penelitian ini adalah untuk menganalisis kemampuan berfikir kritis mahasiswa dalam memecahkan masalah  ditinjau dari perbedaan gender.Analisis ketrampilan berfikir kritis dalam penelitian ini menggunakankriteria dari Ennisyang terdiri dari Focus, Reason, Inference, Situation, Clarity, and Overview.Penelitian ini menunjukkan perbedaan gender secara signifikan mempengaruhi caradan kemampuan berfikir kritis mahasiswa. Studi ini memberikan informasi bahwa perempuan lebih baik dari laki-lakidalam hal ketrampilan berfikir kritis danterdapat perbedaan dalam prosesnya.Hasil penelitian ini menambah  pengetahuan tentang berpikir kritis pada pendidikan tinggi dan berguna bagi para praktisi pendidikan dalam memfasilitasi pengembangan keterampilan berpikir kritis.Kata kunci: Ketrampilan berfikir kritis,  gender
EFEKTIVITAS MODEL PEMBELAJARAN GROUP INVESTIGATION BERBANTUAN KARTU SOAL TERHADAP PRESTASI BELAJAR DITINJAU DARI MOTIVASI BELAJAR PADA MATERI TURUNAN FUNGSI ALJABAR
Authors: Medyasari Larasati Tiara , Muhtarom Muhtarom , Sugiyanti Sugiyanti
Published: October 2017

Tujuan penelitian ini adalah untuk mengetahui (1) Apakah ada perbedaan efek antara model pembelajaran menggunakan model Group Investigation berbantuan kartu soal dengan model konvensional terhadap prestasi belajar matematika siswa (2) Apakah ada perbedaan efek antara tingkat motivasi tinggi, sedang atau rendah terhadap prestasi belajar matematika siswa (3) Apakah ada interaksi antara model pembelajaran dan motivasi belajar terhadap prestasi belajar matematika siswa. Populasi dalam penelitian ini adalah seluruh siswa kelas XI SMA Negeri 5 Semarang. Teknik pengambilan sampel yang digunakan adalah cluster random sampling sehingga terpilih kelas XI IPA 3 yang diberikan model Group Investigation berbantuan kartu soal dan kelas XI IPA 9 yang diberikan model pembelajaran konvensional. Teknik pengumpulan data yang digunakan adalah menggunakan angket untuk data motivasi belajar siswa dan tes untuk data prestasi belajar. Berdasarkan uji  prasyarat disimpulkan bahwa sampel berdistribusi normal, mempunyai variansi yang sama, dan mempunyai kemampuan awal yang sama. Hasil penelitiannya adalah (1)  yang berarti bahwa model pembelajaran group investigation berbantuan kartu soal lebih efektif daripada model pembelajaran konvensional (2)  yang berarti ada perbedaan efek antara siswa dengan kategori motivasi tinggi, sedang dan rendah terhadap prestasi belajar siswa. Prestasi belajar matematika siswa yang mempunyai motivasi belajar tinggi lebih baik daripada siswa yang mempunyai motivasi belajar sedang dan rendah, prestasi belajar matematika siswa yang mempunyai motivasi belajar sedang lebih baik daripada siswa yang mempunyai motivasi belajar rendah (3)  yang berarti bahwa tidak ada interaksi antara model pembelajaran dan motivasi belajar terhadap prestasi belajar matematika pada pokok bahasan turunan fungsi aljabar.Kata Kunci: group investigation, kartu soal, prestasi belajar, motivasi belajar
PENGEMBANGAN COMIC MATH DENGAN PENDEKATAN ETNOMATEMATIKA PADA METERI KUBUS DAN BALOK DI SMP
Authors: Nida Izza Khoirin , Buchori Achmad , Murtianto Yanuar Hery
Published: October 2017

Era teknologi dan informasi yang semakin pesat akan membuat terkikisnya nilai budaya. Budaya yang berkaitan dengan konsep-konsep matematika  biasa disebut etnomatematika. Proses pembelajaran tidak akan efektif dan menarik apabila guru hanya ceramah tentang hal-hal yang terjadi. Untuk itulah diperlukan suatu media yang dapat dilihat, dapat didengar dan dapat dibaca oleh siswa. Penelitian ini bertujuan untuk mengembangkan media berbasis comic math dengan pendekatan etnomatematika yang valid dan efektif pada materi kubus dan balok. Penelitian ini dilaksanakan di SMP IT Assa’idiyyah Kirig Mejobo Kudus pada tanggal 29 April sampai 16 Mei 2017. Desain penelitian ini menggunakan model pengembangan yang dimodifikasi oleh Sukmadinata yaitu: (1) Studi Pendahuluan (2) Pengembangan Model (3) Uji Model. Tetapi pada penelitian ini hanya sampai pengembangan model. Pada tahap pertama yaitu studi pendahuluan terdiri dari studi kepustakaan tentang komik dan etnomatematika. Selanjutnya survei lapangan dilakukan untuk mengetahui kemampuan dan minat belajar siswa. Lalu penyusunan produk awal meliputi (1) Menentukan karakter dalam comic math (2) Menyusun alur cerita dalam comic math (3) Membuat desain media comic math. Pada tahap kedua yaitu pengembangan model yaitu uji coba terbatas yang mengambil 2 buah kelas, kelas VIII A sebagai kelas kontrol menggunakan pembelajaran konvensional dan kelas VIII Tahfidz sebagai kelas eksperimen menggunakan media comic math dengan pendekatan etnomatematika. Uji keefektifan produk ditunjukkan dari hasil belajar kelas eksperimen lebih baik dibandingkan kelas kontrol menggunakan uji t pihak kanan, dengan analisis menggunakan uji t didapatkan hasil thitung>ttabel yaitu 2,68>1,67722, artinya pembelajaran dengan menggunakan comic math dengan pendekatan etnomatematika lebih baik dibandingkan dengan pembelajaran konvensional.  Kata kunci: Komik, Comic Math, Pendekatan Etnomatematika
CROSS-CUTTING : PEMBENTUKAN KONFLIK DALAM FILM “HAJI BACKPACKER”
Authors: Mulia Prajanata Bagiananda
Published: October 2017

Cross–cutting, sebuah teknik dalam editing film dengan memainkan dua situasi adegan berbeda ruang, yang seperti akan bertemu namun kenyataannya tidak. Sutradara film Haji Backpacker melalui peran editornya menyusun urutan gambar menggunakan teknik- teknik tertentu, seperti yang dominan terlihat pada film Haji Backpacker yaitu penerapan teknik cross-cutting. Penggambaran adegan di luar satu kesatuan cerita seperti adegan mimpi, adegan masa lalu, dan sejenisnyadigunakan untuk meningkatkan ketegangan, menampilkan konflik, dan menunjukkan titik perbandingan ataupun perbedaan. Penelitian ini mencoba membedah bagaimana sebuah teknik sederhana dalam editing filmseperti cross-cutting yang mencoloktampak pada film Haji Backpacker mempunyai peran kuat dalam gaya bercerita sehingga mempengaruhi pembentukan konflik cerita. Teknik cross- cuttingdilihat dari bagaimana dan mengapa ia muncul, hingga pemaknaan pada konflik internal maupun eksternal yang ditimbulkan terhadap film Haji Backpacker. Hasil dari penelitian ini bahwa konflik mampu dilihat dan dibentuk melalui teknik cross-cutting yang selalu terikat dalam suatu tema besar tiap kemunculannya
Making English Learner Reclassification to Fluent English Proficient Attainable or Elusive: When Meeting Criteria Is and Is Not Enough
Authors: Estrada Peggy , Wang Haiwen
Published: October 2017

Employing longitudinal, multisite comparative mixed-methods, we describe patterns of reclassifying and not reclassifying eligible English learner (EL) students to fluent English proficient, and we identify factors impeding and facilitating reclassification. Analyses of administrative data for 7 cohorts of students over 3 years in one district and 2 years in another revealed a considerable number of students meeting all criteria, and a nonoverlapping group meeting at least standardized-test criteria, were not reclassified, implicating this practice in the production of long-term EL status. However, the rate of not reclassifying was more than 2 to 5 times higher in one district than the other. Analyses of policy documents, reclassification decision forms, staff interviews, and surveys revealed that undergirding these differences were distinct reclassification policies and practices. We discuss policy, practice, and research implications, including issues of opportunity to learn, equity, and the need for a common definition of ELs involving a common set of specific criteria and standardized processes for reclassification statewide.
Comparative Analysis of Toll Plaza Safety Features in Puerto Rico and Massachusetts with a Driving Simulator
Authors: Valdés Didier , Colucci Benjamín , Knodler Michael , Fisher Donald , Ruiz Bryan , Ruiz Johnathan , García Ricardo , Colón Enid , Hajiseyedjavadi Foroogh
Published: October 2017

Driving simulators have been widely used in transportation research and have potential applications for toll plaza safety research. The University of Puerto Rico at Mayagüez (UPRM) and the University of Massachusetts, Amherst (UMass-Amherst) performed a collaborative investigation using driving simulators to evaluate drivers’ behavior in two toll plazas with different signage and lane configurations that operate under the U.S. jurisdiction. The studied toll roads were the Caguas South Toll Plaza in Puerto Rico and the West Springfield Toll Plaza in Massachusetts. The major safety issues identified in both toll roads were unexpected lane changes, sudden vehicle stops, and variable speed patterns. The purpose of this study was to exchange research scenarios between UPRM and UMass-Amherst to test drivers who were unfamiliar with the areas of the study and enlarge the scope. Assuming that the patterns of behavior were similar, the results would suggest that drivers’ behaviors from different regions depend largely on the geometry of the toll plaza and not on the driving culture particular to a region. This study will greatly add to the utility of driving simulator studies because the results reported from one region and one toll plaza arrangement should generalize to other regions around the country and to territories. Results show that familiar drivers had a better driving performance, with respect to variability of lane position, when compared with unfamiliar drivers. However, the proposed treatments for each toll plaza improved road safety for both familiar and unfamiliar drivers.
Strategies to Assist Drivers in Remaining Attentive While Under Partially Automated Driving: Verification of Human–Machine Interface Concepts
Authors: Llaneras Robert E. , Cannon Brad R. , Green Charles A.
Published: October 2017

Visual inattention is a major concern with partially automated driving systems that assume vehicle steering functions. The safety concept for these systems capable of maintaining vehicle lane position and headway depends on an attentive driver who detects and appropriately responds to objects and events that are beyond the limitations of the sensors. Embedded within a proposed system are features designed to help drivers perform these functions and remain attentive to the driving environment. This study served to validate human–machine interface (HMI) strategies and concepts that can be applied to production-intent partially automated system HMI to achieve intended safety goals in assisting drivers to maintain attention to driving. Previous validation efforts, conducted as part of a NHTSA study, proved insufficient for verification of these driver performance functions since they relied on an incomplete version of alternative HMI concepts. The current study, with a sample of 25 licensed drivers, used approaches that more closely approximated the potential production-intent partially automated HMI concepts, including the introduction of consequences for failing to respond to alerts. Work was performed by using an advanced prototype capable of mimicking the basic functions afforded in a partially automated system. Driver responses to unexpected lane drift events were also examined. Results found that HMI concepts that introduce consequences for driver nonresponse situations substantially increase driver compliance to system cues, prompts, and alerts. Results of this study suggest that the potential production design partially automated system HMI concepts can assist drivers in maintaining their attention to driving.
Effects of Alert Cue Specificity on Situation Awareness in Transfer of Control in Level 3 Automation
Authors: Wright Timothy J. , Agrawal Ravi , Samuel Siby , Wang Yuhua , Zilberstein Shlomo , Fisher Donald L.
Published: October 2017

Drivers in a Level 3 automation environment typically need at least 8 s following a manual takeover request to achieve appropriate levels of situation awareness. Studies that have derived this time estimate use general audio alerts that suggest a transfer of control from the automation to the driver might be required. The current experiment examined if improvements in younger drivers’ situation awareness might be observed in as little as 4 s before a latent hazard might materialize and a transfer of control occurs if more specific audio alerts are used. Younger drivers either drove manually with no cue or in one of four automation conditions: ( a) a general cue condition, ( b) a condition that described the risky features of the roadway and the location of those features, ( c) a condition that contained information about the actual identity of the threat and the required behavior, and ( d) a combination cue condition (both environment and threat cue). Eye movements were recorded as drivers completed six scenarios in a simulated automated driving experiment. The results showed that audio cues that contained information about risky roadway features increased the detection of latent hazards by almost 40% compared with when a general cue or a threat cue was used. Performance with the combined cue was no better than performance with the environment cue. The environment cue gives drivers the critical seconds needed to mitigate a potential crash. Results are informative about which types of alerts to use to inform drivers of upcoming hazards.
On-Road Visual Sign Salience, Driver Attention Allocation, and Target Detection Accuracy
Authors: Zahabi Maryam , Pankok Carl , Kaber David B. , Machado Patricia , Lau Mei Ying , Hummer Joseph E. , Rasdorf William
Published: October 2017

Previous studies have empirically assessed the effect of on-road signage on driver distraction and attention allocation through eye-tracking measures and driving simulations. However, state and federal agencies might be able to make use of simpler approaches to determining the potential visual load of on-road signs. This study compared different on-road signage (food, gas and attraction, and distance guide signs) with respect to visual salience, assessed the effect of the number of panels and logo format on signage salience, and analyzed associations between salience values for different sign types with target detection accuracy and off-road glance duration. Visual salience of signs was measured with the salience using the natural statistics (SUNs) method. For correlation analyses between sign salience, attention allocation, and detection accuracy, a sample of 120 drivers participated in two driving simulation studies. Results revealed food business signs, containing all pictorial logos, to be more salient than gas and attraction and distance guide signs. In addition, results revealed that increasing the number of sign panels from six to nine significantly increased visual salience. It was also found that attraction signs including all pictorial logos were more salient than signs with text-based logos. Results did not reveal statistically significant relationships between visual salience and attention allocation. In addition, there was no significant correlation between target detection accuracy and visual salience for various sign types. Future work with a higher sign-sampling rate is needed to assess whether the SUNs method is a useful measure for determining if roadway sign salience is a driving factor in distraction.
Age-Based Simulation of Merging Behavior at Freeway Merging Ramps
Authors: Lwambagaza Lina , Sando Thobias , Mtoi Enock , Ozguven Eren Erman , Sobanjo John Olusegun
Published: October 2017

In this research, VISSIM, a microscopic traffic simulation software, was used to evaluate the influence of drivers’ age on the operations of a typical diamond interchange. Data were collected on two merging sections along I-75 in Southwest Florida at free-flow traffic condition to get enough samples for driver’s age group. Several measures of effectiveness were collected, including speeds, gaps, and location of entry to the main-line lanes. This information was used as either model input or for verification purposes in the validation process. Two VISSIM models were developed for each site: one model for the existing conditions and verification and another model for a sensitivity analysis, varying the percentage of older drivers and level of service (LOS from A to E) to determine their influence on ramp merging operational characteristics. At 95% confidence level, the results indicate that merging speed is a significant factor influencing the merging location. Older drivers have low merging speeds compared with middle-age and younger drivers. The changes in LOS were found to influence the selection of the merging location for all drivers, whereby at LOS E, most drivers tend to merge near the end of the acceleration lane.
Linking the Detection Response Task and the AttenD Algorithm Through Assessment of Human–Machine Interface Workload
Authors: Lee Joonbum , Sawyer Ben D. , Mehler Bruce , Angell Linda , Seppelt Bobbie D. , Seaman Sean , Fridman Lex , Reimer Bryan
Published: October 2017

Multitasking related demands can adversely affect drivers’ allocation of attention to the roadway, resulting in delays or missed responses to roadway threats and to decrements in driving performance. Robust methods for obtaining evidence and data about demands on and decrements in the allocation of driver attention are needed as input for design, training, and policy. The detection response task (DRT) is a commonly used method (ISO 17488) for measuring the attentional effects of cognitive load. The AttenD algorithm is a method intended to measure driver distraction through real-time glance analysis, in which individual glances are converted into a scalar value using simple rules considering glance duration, frequency, and location. A relationship between the two tools is explored. A previous multitasking driving simulation study, which used the remote form of the DRT to differentiate the demands of a primary visual–manual human–machine interface from alternative primary auditory–vocal multimodal human–machine interfaces, was reanalyzed using AttenD, and the two analyses compared. Results support an association between DRT performance and AttenD algorithm output. Summary statistics produced from AttenD profiles differentiate between the demands of the human–machine interfaces considered with more power than analyses of DRT response time and miss rate. Among discussed implications is the possibility that AttenD taps some of the same attentional effects as the DRT. Future research paths, strategies for analyses of past and future data sets, and possible application for driver state detection are also discussed.
Modeling Effects of Forward Glance Durations on Latent Hazard Detection
Authors: Park Hyoshin , Gao Song , Samuel Siby
Published: October 2017

Performance of in-vehicle, secondary tasks requires a driver to alternate his or her glances between the inside of the vehicle and the forward roadway. While previous research has shown that thresholds of off-road and durations are critical to latent hazard detection, there has been no research to predict the probability of hazard detection in a time series considering all possible forward glance durations. To determine the minimum forward roadway duration to adequately anticipate hazards, 45 drivers were asked to navigate eight unique virtual scenarios on a driving simulator while alternating their glances inside (2s) and outside (1s, 2s, 3s, or 4s) the vehicle in a uniform sequence (consistent on-road and off-road durations). A microbenchmark approach based on Hidden Markov models is explored to infer the transition probability of hazard detection that changes dynamically between the detection and nondetection stages. The model is cross validated and demonstrated to be accurate and robust. Three characteristics of total sequence time were tested in the model. Using the ground truth transition probability from fixed duration, the probability of hazard detection with variable duration within an alternation sequence was computed. Across nonuniform alternation sequences, different permutations of sequences show that a short time series of alternation (10s) of glance behavior is sufficient for hazard detection (greater than 50.0%). Appropriate countermeasures can be developed to increase a driver’s forward glance duration whenever the detection probability is predicted low.
Investigating Driver Behavior at Minor-Street Stop-Controlled Intersections in Qatar
Authors: Shaaban Khaled , Wood Jonathan S. , Gayah Vikash V.
Published: October 2017

Stop-controlled intersections are dangerous locations in which drivers must negotiate conflicts between traffic streams. This study examined driver stopping compliance at minor-street stop-controlled intersections in Qatar. Several variables that may influence driver behavior when approaching a stop sign were considered—including age, gender, driver heritage differences, vehicle type, presence of an approaching vehicle or a pedestrian, peak and nonpeak hours, weekday versus weekend, and residential versus commercial land use. Binary and ordinal logistic regression models were developed to describe driver stopping behavior as functions of these characteristics. Results indicated an alarmingly low compliance rate with minor-street stop signs. Generally, results indicated that male drivers, young drivers, and SUV drivers are less likely to come to a complete stop at these locations. Results also revealed that drivers are more likely to ignore the stop sign when they notice a vehicle or pedestrian approaching and most likely to beat the approaching vehicle or pedestrian through the intersection and reduce intersection-related delay. These findings raise a major safety concern and indicate aggressive driving tendencies. Potential countermeasures include increasing police enforcement, initiating traffic safety campaigns (e.g., targeting the higher risk drivers identified in the results), and improving the visibility of stop signs using different measures, such as larger and additional stop signs, “Stop Ahead” advance traffic control signs, and enhanced pavement markings.
Crash Heterogeneity: Implications for Naturalistic Driving Studies and for Understanding Crash Risks
Authors: Knipling Ronald R.
Published: October 2017

Motor vehicle crashes are heterogeneous in their conditions of occurrence, risk factors, and causal scenarios. Horizontal heterogeneity refers to the many distinct scenarios within any crash severity level. Vertical heterogeneity is seen in the different proportions of characteristics at different severity levels. Evidence is presented for the causal heterogeneity of crashes involving all motor vehicles and specifically for large trucks. If horizontally or vertically defined crash subsets are not representative of other subsets, then findings from them cannot be validly generalized to other populations. Furthermore, crash heterogeneity contradicts a key assumption of the Heinrich Triangle, the assumption that crashes within the triangle have identical or highly similar causal factors regardless of outcome severity. The Heinrich Triangle assumption is explicit in naturalistic driving studies (NDS) capturing mainly noncrash dynamic events and minor crashes below conventional reporting thresholds. NDS causal prevalence estimates have little likely validity in relation to fatal and injury crashes where the preponderance of human harm occurs. NDS external validity could perhaps be improved by post hoc mathematical indexing of captured events to the objective profiles of target populations.
Effects of a Change in Environment on the Minimum Time to Situation Awareness in Transfer of Control Scenarios
Authors: Agrawal Ravi , Wright Timothy J. , Samuel Siby , Zilberstein Shlomo , Fisher Donald L.
Published: October 2017

From previous experiments, it is known that control must be transferred to the driver in a Level 3 vehicle at least 8 s before the driver passes a latent hazard for the driver to be as aware of the latent hazard as the driver is when glancing continuously on the forward roadway. In these experiments, the driving environment remained consistent throughout the time the automated driving suite (ADS) was engaged, and immediately after control was transferred to the driver. Considering that drivers expect different categories of hazards in different driving environments, a transition to a different environment while the ADS is engaged may impair a driver’s ability to both achieve situation awareness and successfully mitigate hazards. The current experiment examined if 8 s was enough time for drivers to achieve situation awareness and appropriately mitigate hazards when the roadway environment changes while the driver is engaged in a secondary activity that takes his or her eyes away from the forward roadway. Drivers’ eye movements and vehicle metrics were recorded as they completed one of three conditions in a driving simulator: an automation condition where the driving environment remained consistent throughout; an automation condition that contained some transitions to a new environment while the driver engaged the ADS; and a manual driving condition that also contained the same transitions as the latter automation condition. Results suggest that even 8 s is not enough time for drivers to achieve situation awareness and mitigate hazards when the hazards are unexpected.
Analyzing and Modeling Drivers’ Deceleration Behavior from Normal Driving
Authors: Deligianni Stavroula Panagiota , Quddus Mohammed , Morris Andrew , Anvuur Aaron , Reed Steven
Published: October 2017

Most research in vehicle automation has mainly focused on the safety aspect with only limited studies focusing on occupants’ discomfort. To facilitate their rapid uptake and penetration, autonomous vehicles (AVs) should ensure that occupants are both safe and comfortable. Recent research, however, revealed that people felt uncomfortable when AVs braked. This may be caused by the robotlike braking performance. Existing studies on drivers’ braking behavior investigated data from either controlled experiments or driving simulators. There is a dearth of research on braking behavior in normal driving. The objective of the study was to examine drivers’ braking behaviors by exploiting naturalistic driving data from the Pan-European TeleFOT project (Field Operational Tests of Aftermarket and Nomadic Devices in Vehicles). On a fixed route of 16.5 km, 16 drivers were asked to drive an instrumented vehicle. About 11 million observations were analyzed to identify the profile, value, and duration of deceleration events. Since deceleration events are nested within trips and trips within drivers, multilevel mixed-effects linear models were employed to develop relationships between deceleration value and duration and the factors influencing them. Results indicate that the most-used profile of the deceleration behavior follows a hard braking at the beginning when detecting a danger and then becomes smoother. Furthermore, the results suggest that the speed, reason for braking, and deceleration profile mostly affect the deceleration events. Findings from this study should be considered in examining the braking behavior of AVs.
Retreatment of vestibular schwannoma with Gamma Knife radiosurgery: clinical outcome, tumor control, and review of literature
Authors: Fu Victor X. , Verheul Jeroen B. , Beute Guus N. , Leenstra Sieger , Kunst Henricus P. M. , Mulder Jef J. S. , Hanssens Patrick E. J.
Published: October 2017

OBJECTIVE

Gamma Knife radiosurgery (GKRS) has become an accepted treatment for vestibular schwannoma, with a high rate of tumor control and good clinical outcome. In a small number of cases, additional treatment is needed. This retrospective study examines the clinical outcome, reproducibility of volumetric response patterns, and tumor control rate after administering a second GKRS to treat vestibular schwannomas.

METHODS

A total of 38 patients were included: 28 patients underwent a radiosurgical procedure as the initial treatment (Group 1), and 10 patients underwent microsurgical resection with adjuvant radiosurgery on the tumor remnant as the initial treatment (Group 2). The indication for a second GKRS treatment was growth observed on follow-up imaging. The median margin dose was 11.0 Gy for the first procedure and 11.5 Gy for the second procedure. Tumor control after retreatment was assessed through volumetric analysis. Clinical outcome was assessed through medical chart review.

RESULTS

Median tumor volume at retreatment was 3.6 cm3, with a median treatment interval of 49 months. All patients showed tumor control in a median follow-up period of 75 months after the second radiosurgical procedure. Volumetric tumor response after the second procedure did not correspond to response after the first procedure. After retreatment, persisting House-Brackmann Grade II facial nerve dysfunction was observed in 3 patients (7.9%), facial spasms in 5 patients (13%), and trigeminal nerve hypesthesia in 3 patients (7.9%). Hearing preservation was not evaluated because of the small number of patients with serviceable hearing at the second procedure.

CONCLUSIONS

Repeat GKRS after a failed first treatment appears to be an effective strategy in terms of tumor control. The volumetric response after a repeat procedure could not be predicted by the volumetric response observed after first treatment. This justifies considering repeat GKRS even for tumors that do not show any volumetric response and show continuous growth after first treatment. An increased risk of mild facial and trigeminal nerve dysfunction was observed after the second treatment compared with the first treatment.
The V3 segment of the vertebral artery as a robust donor for intracranial-to-intracranial interpositional bypasses: technique and application in 5 patients
Authors: Tayebi Meybodi Ali , Benet Arnau , Lawton Michael T.
Published: October 2017

The V3 segment of the vertebral artery (VA) has been studied in various clinical scenarios, such as in tumors of the craniovertebral junction and dissecting aneurysms. However, its use as a donor artery in cerebral revascularization procedures has not been extensively studied. In this report, the authors summarize their clinical experience in cerebral revascularization procedures using the V3 segment as a donor. A brief anatomical description of the relevant techniques is also provided.