Reliability Analysis of Complex NASA Systems with Model-Based Engineering

The emergence of model-based engineering, with Model- Based Systems Engineering (MBSE) leading the way, is transforming design and analysis methodologies. The recognized benefits to systems development include moving from document-centric information systems and document-centric project communication to a model-centric environment in which control of design changes in the life cycles is facilitated. In addition, a single source of truth about the system, that is up-to-date in all respects of the design, becomes the authoritative source of data and information about the system. This promotes consistency and efficiency in regard to integration of the system elements as the design emerges and thereby may further optimize the design. Therefore Reliability Engineers (REs) supporting NASA missions must be integrated into model-based engineering to ensure the outputs of their analyses are relevant and value-needed to the design, development, and operational processes for failure risks assessment and communication

Ekspresi Musikal Ratok Sikambang dalam Babiola

Tulisan ini merupakan hasil penelitian tentang pertunjukan biola yang oleh masyarakat Batang kapas dikenal dengan istilah babiola. Penelitian bertujuan untuk mengetahui dan menganalisis salah satu repertoar lagu dalam pertunjukan biola tersebut yang sangat dikenal oleh masyarakat setempat, yaitu Ratok Sikambang. Penelitian ini menerapkan metode kualitatif dengan pendekatan semiotik sebagai simbol budaya. Hasil penelitian memperlihatkan, bahwa tradisi babiola (pertunjukan biola) dengan Ratok Sikambang-nya merupakan simbol sosial masyarakat. Biola itu sendiri adalah sejenis alat musik tradisional yaitu sejenis instrumen gesek mirip biola (viol), dengan materi utamanya adalah penyampaian teks kaba (cerita). Salah satu repertoar lagunya yang terkenal adalah Ratok Sikambang. Ratok Sikambang diyakini sebagai lagu tradisional tertua dan memiliki karakteristik melodi dan teks. Isi teks lagu berupa imitasi bentuk isak tangis ratapan yang dipandang masyarakat pendukungnya sebagai representasi suasana sedih. Hal ini dialami tokoh legendaris Sikambang yang selalu dirundung penderitaan hidup. Penyajian tradisi Babiola dalam membawakan karakter lagu Ratok Sikambang disajikan secara ekspresif oleh tukang biola (pemain biola) sebagai puncak ekspresi musikal

Penggunaan Limbah Botol Plastik Sebagai Agregat Pada Campuran Beton Dengan Penambahan Silika Fume

Penelitian yang dilakukan dengan metode eksperimental ini dimaksudkan untuk memanfatkan limbah botol plastik jenis PET dalam campuran beton. Pemilihan bahan limbah botol plastik dengan penambahan silika fume 5% dalam campuran beton meliputi pengujian kuat tekan yang dilakukan pada benda uji kubus ukuran 15 cm x 15 cm x 15 cm sebanyak 16 benda uji, dengan faktor air semen ( FAS ) yang digunakan adalah 0,6. Penelitian ini menggunakan limbah botol plastik jenis PET yang tertahan pada saringan 9,52 mm dan di substitusikan dengan volume agregat kasar pada beton normal serta dengan penambahan silika fume yang mengandung kadar SiO2 yang dapat menggantikan semen. Adapun untuk komposisi campuran beton untuk limbah botol plastik adalah 25%, 50% dan 75% dengan penambahan silika fume setiap variasinya. Berdasarkan hasil pengujian beton dengan limbah botol plastik komposisi 25% diperoleh kuat tekan karateristik (σ\u27bk) sebesar 164,99 kg/cm2, untuk limbah botol plastik komposisi 50% diperoleh kuat tekan karateristik (σ\u27bk) sebesar 138,50 kg/cm2, dan untuk limbah botol plastik komposisi 75%, diperoleh kuat tekan karateristik (σ\u27bk) sebesar 111,31 kg/cm2. Persentase penurunan dengan kadar campuran 25%, 50%, dan 75% jika dibandingkan dengan beton normal adalah sebesar 24%, 37%, dan 49% turun dari kuat tekan karakteristik beton normal.Kata-kata kunci: limbah botol plastik jenis PET, silika fume, faktor air semen ( FAS) 0,6. PENDAHULUANLimbah botol plastik merupakan polyester termoplastik yang diproduksi secara komersial melalui produk kondensasi yang dikarakterisasi dengan banyaknya ikatan ester yang didistribusikan sepanjang rantai utama polimer. Limbah botol plastik merupakan bahan dasar dari botol minuman plastik, dengan nama polioksi etilen neooksitereftaoil. Limbah botol plastik yang berupa polyetylene terephtalate (PET) akan dimanfaatkan dalam penelitian ini.Silika fume dalam jumlah tertentu dapat menggantikan jumlah semen, selain itu karena Silika fume mempunyai diameter sangat kecil, maka Silika fume dapat juga berperan sebagai pengisi diantara pertikel- partikel semen. Dengan adanya Silika fume ini distribusi porositas beton menjadi lebih kecil karena peran Silika fume disini selain sebagai penanggulangan terhadap serangan sulfat juga sebagai pengisi rongga- rongga partikel semen dan agregat sehingga dapat menambah kekedapan dan keawetan beton

Identifiability of generalised Randles circuit models

The Randles circuit (including a parallel resistor and capacitor in series with another resistor) and its generalised topology have widely been employed in electrochemical energy storage systems such as batteries, fuel cells and supercapacitors, also in biomedical engineering, for example, to model the electrode-tissue interface in electroencephalography and baroreceptor dynamics. This paper studies identifiability of generalised Randles circuit models, that is, whether the model parameters can be estimated uniquely from the input-output data. It is shown that generalised Randles circuit models are structurally locally identifiable. The condition that makes the model structure globally identifiable is then discussed. Finally, the estimation accuracy is evaluated through extensive simulations

Taxonomies of money laundering: an Iranian perspective

Purpose This study aims to identify the sources of laundered money in Iran and the destinations to which it is transferred, independently verified by auditors. Based on such data, the study aims to develop a simple model of endogenous and exogenous factors facilitating money laundering in developing countries, which can inform domestic and international legislative and regulatory responses. Design/methodology/approach Questionnaires were sent to Iranian certified public accountants who worked for auditing firms in 2019 and who have encountered suspected money laundering during their work with clients. Findings The government and public officials are the primary sources of money laundering activity in Iran. The main destinations of laundered funds are investments abroad, gold, foreign currencies, real estate and purchases of luxury goods. Domestic legislation, while bearing similarities with that found in other jurisdictions such as the UK and the USA, is flawed in several ways, including an inability to determine beneficial ownership of funds and weak enforcement. Originality/value Because of international sanctions and the prevailing political situation, it is difficult to obtain data for money laundering and other financial crimes in Iran. The data obtained is of importance to international bodies in understanding the nature of money laundering in Iran, and how to negotiate in the future to address mutual concerns. Given the country’s perceived high association with money laundering, the data obtained is of value in identifying the specific characteristics of the problem

Perception versus reality: Iranian banks and international anti-money laundering expectations

Purpose Iran has been ranked by the Basel Committee on Banking Supervision and the Financial Action Task Force (FATF) as one of the foremost countries in the world for money laundering. However, Iranian banks claim that they comply with international standards for reporting suspicious activity, risk management and training. This paper aims to investigate this dichotomy between perception and reality. Design/methodology/approach A Wolfsberg-style questionnaire was sent to partners in Iranian accounting firms, which have audited domestic banks over the past five years to investigate the adequacy of risk management systems. Findings Most Iranian banks have anti-money laundering (AML) systems, which compare favourably with those of international counterparties. Banks take a risk-based approach to potential criminal behaviour. The negative perception of Iranian banks is principally attributable to the government’s unwillingness to accede to “touchstone” international conventions. In spite of having in place AML laws, which are comparable in intent with those of the UK and the United States of America (USA), weak enforcement remains a significant impediment of which the political establishment is aware. Practical implications Measures required to bring Iranian banks into compliance with international standards may be less extensive than perceptions suggest. However, failure of the government to accede to conventions stipulated by the FATF means that banks may remain ostracised by foreign counterparties for the foreseeable future. Originality/value This study provides a unique insight into the extent of AML compliance in Iranian banks as verified by external auditors

Multiple proton diffusion and film densification in atomic layer deposition modeled by density functional theory

To investigate the atomic layer deposition (ALD) reactions for growth of HfO2 from Hf(NMe2)4 (TDMAHf) andH2O, a density functional theory (DFT) slab model was employed. We inspected all energy steps, from the early stage of adsorption of each ALD precursor to the densification of multiple atoms into bulk-like HfO2 layers. The activation energy calculations show that repeated proton diffusion from the surface to amide ligands and rotation of the protonated amine is more energetically accessible than the simple elimination of the amine in the initial stage. We therefore propose that multiple protons diffuse to the amide ligands of the Hf precursor before desorption of protonated ligands takes place. Loss of a proton from surface oxygen frees it up for bonding to Hf of the precursor. Protonation of ligands, and especially desorption of ligands, frees up Hf for bonding to surface oxygen. These effects are termed “densification”, as they bring Hf−O packing closer to the bulk scenario. Densification is associated with substantial release of energy. During the metal pulse, saturation of the surface by remaining fragments HfX causes adsorption of further metal precursor to stop. The presence of these fragments prevents further chemisorption of HfX4, since this requires the creation of a strong dative bond between Hf and O. Next, during the H2O pulse, Hf exchanges its remaining ligands with OH groups. The exchange occurs due to the decomposition of adsorbed H2O molecules in clusters of HfX. Decomposition of H2O when adsorbed onto a (Hf(NMe2))x (x ≥ 2) cluster (e.g., dimers) also increases the coordination of Hf and O. Simultaneously, low-coordinated oxygen atoms appear at the surface, which are reactive sites for the next metal pulse. With saturation of the surface by OH groups, H2O molecules begin to appear. This detailed description of ALD chemistry allows us to make qualitative predictions about how the process depends on temperature. The data can also be inputted into kinetic simulations for a quantitative view of the complex film growth process

Cooperation between adsorbates accounts for the activation of atomic layer deposition reactions

Atomic layer deposition (ALD) is a technique for producing conformal layers of nanometre-scale thickness, used commercially in non-planar electronics and increasingly in other high-tech industries. ALD depends on self-limiting surface chemistry but the mechanistic reasons for this are not understood in detail. Here we demonstrate, by first-principle calculations of growth of HfO2 from Hf(N(CH3)2)4–H2O and HfCl4–H2O and growth of Al2O3 from Al(CH3)3–H2O, that, for all these precursors, co-adsorption plays an important role in ALD. By this we mean that previously-inert adsorbed fragments can become reactive once sufficient numbers of molecules adsorb in their neighbourhood during either precursor pulse. Through the calculated activation energies, this ‘cooperative’ mechanism is shown to have a profound influence on proton transfer and ligand desorption, which are crucial steps in the ALD cycle. Depletion of reactive species and increasing coordination cause these reactions to self-limit during one precursor pulse, but to be re-activated via the cooperative effect in the next pulse. This explains the self-limiting nature of ALD