741 research outputs found
Pengamanan Data Menggunakan Metoda Enkripsi Einstein
Dalam proses demokrasi maka semua orang bebas untuk berbicara mengutarakan pendapat dan pandangannya berdasarkan pribadi dan perasaannya, tentu saja dengan melihat bahwa hak demokrasinya tersebut tidak melanggar hak demokrasi orang lain. Kebebasan berkomunikasi ini juga termasuk kebebasan untuk berbicara dengan orang yang diinginkan. Untuk itu akan sangat mengganggu bila isi pembicaraan terutama yang menggunakan teknologi informasi ternyata bocor kepada orang yang tidak berhak dan secara demokrasi ini melanggar haknya, padahal dalam teknologi informasi yang berkembang secara sangat pesat ini ternyata tidak dibarengi dengan penggunaan alat untuk pengamanan data yang tepat dalam sistem informasi. Salah satu teknik pengamanan data informasi di dunia internet adalah penggunaan teknik algoritma kriptografi. Suatu algoritma kriptografi berisi fungsi-fungsi matematika yang digunakan untuk melakukan proses enkripsi dan dekripsi. Algoritma kriptografi yang digunakan merupakan jenis algoritma kriptografi simetrik yang menggunakan kunci rahasia yang sama untuk proses enkripsi dan dekripsinya. Pada makalah ini dipaparkan penggunaan algoritma kriptografi Einstein sebagai salah satu cara untuk mengamankan data. Pada algoritma Einstein, terdapat proses acak (random) yang menggunakan metoda kongruensial linear. Algoritma Einstein mempunyai kelebihan dalam melakukan proses enkripsi dan dekripsi pada hampir semua jenis file yang umum digunakan. Algoritma Einstein bisa diimplementasikan untuk semua ukuran file
Green Vehicle Routing Problems in the New Mobility Era
The rapid advances in wireless communication and ubiquitous mobile is changing the way people and goods move in the new mobility era. The world’s population is increasingly city-based. Urban mobility becomes one of the toughest challenges that cities face. On the one hand, the fast growing e-commerce industry has resulted in the increasing volume of goods transportation, as well as the increasing demand for freight transportation service in terms of delivery time and reliability by consumers. On the other hand, the growing environmental concerns (e.g., fuel consumption, land use, Greenhouse Gas emissions) are taking center stage. These factors have put enormous pressure on the freight carriers to meet this last-mile challenge in transportation cost, delivery time and reliability. A new generation of efficient, timely, reliable, green transportation system becomes the answer of these various problems.
This dissertation aims at building a novel system that simultaneously achieves a maximization of carrier’s net profit and significantly diminishes the negative effects of freight transportation on the environment. It is of critical importance for the logistics industry to fully exploit the potential to be more efficient, flexible and sustainable. To obtain this objective, one of the most important technical cores needs to be considered is the eco-routing tool that minimizes the total transportation system cost due to travel time, fuel consumption as well as vehicular emission under different frameworks of various vehicle routing problems.
Specifically, this research concentrates on three vehicle routing problems in the context of the new mobility era, namely Green Same Day Package Delivery Service with Real-time Demand, Electric Vehicle Routing Problem with Flexible Recharging and An Ad Hoc Peer-to-Peer Transshipment and Same Day Delivery Problem. These research efforts aim to tackle the following major challenges in freight industry: pre-scheduled and single shipment oriented delivery, dangerous effects on environment caused by conventional vehicle emissions, inefficient service and lack of collaboration among logistics carriers respectively.
This proposed research makes significant scientific contributions to the vehicle routing literature in model formulation and algorithm design in the following aspects: (1) consideration of real-time information in routing, (2) eco-routing by minimizing other harmful pollutants such as particulate matter (PM), (3) fast online algorithms on a mobile platform (e.g., smartphone) applicable to large scale urban delivery, (4) alternative delivery mode of electric vehicles allows flexible recharging (full or partial) en-route and (5) incorporation of the ad-hoc pick-up and delivery requests in transshipment problem.
The products of this research are (1) an eco-routing tool that enables real-time on-the-go cargo consolidation service, (2) an electric vehicle routing tool that helps the penetration of EVs in freight industry, and (3) an ad hoc platform that enables collaboration among couriers such that resources are better utilized. These can be applied to future urban goods delivery e-markets, which will bring customers flexible, timely and economical logistics service while maximizing couriers’ net gain through shared resources enabled by wireless communication and mobile computing. At the same time, the adverse effects of freight transportation on the environment will also be reduced, which makes the urban delivery service system more sustainable
Multiresonant Composite Optical Nanoantennas by Out-of-plane Plasmonic Engineering
Optical nanoantennas
can concentrate light and enhance light-matter
interactions in subwavelength domain, which is useful for photodetection,
light emission, optical biosensing, and spectroscopy. However, conventional
optical nanoantennas operating at a single wavelength band are not
suitable for multiband applications. Here, we propose and exploit
an out-of-plane plasmonic engineering strategy to design and create
composite optical nanoantennas that can support multiple nanolocalized
modes at different resonant wavelengths. These multiresonant composite
nanoantennas are composed of vertically stacked building blocks of
metal–insulator–metal loop nanoantennas. Studies of
multiresonant composite nanoantennas demonstrate that the number of
supported modes depends on the number of vertically stacked building
blocks and the resonant wavelengths of individual modes are tunable
by controlling the out-of-plane geometries of their building blocks.
In addition, numerical studies show that the resonant wavelengths
of individual modes in composite nanoantennas can deviate from the
optical response of building blocks due to hybridization of magnetic
modes in neighboring building blocks. Using Au nanohole arrays as
deposition masks to fabricate arrays of multilayered composite nanoantennas,
we experimentally demonstrate their multiresonant optical properties
in good agreement with theory predictions. These studies show that
out-of-plane engineered multiresonant composite nanoantennas can provide
new opportunities for fundamental nanophotonics research and practical
applications involving optical multiband operations, such as multiphoton
process, broadband solar energy conversion, and wavelength-multiplexed
optical system
Enhancing Bi-functional Electrocatalytic Activity of Perovskite by Temperature Shock: A Case Study of LaNiO<sub>3−δ</sub>
Perovskite
oxide offers an attractive alternative to precious metal
electrocatalysts given its low cost and high oxygen reduction reaction
(ORR) and oxygen evolution reaction (OER) activity. The results obtained
in this work suggest a correlation of crystal structure with ORR and
OER activity for LaNiO<sub>3−δ</sub>. LaNiO<sub>3−δ</sub> perovskites with different crystal structure were obtained by heating
at different temperatures, e.g., 400, 600, and 800 °C followed
by quenching into room temperature. Cubic structure (relative to rhombohedral)
leads to higher ORR and OER activity as well as enhanced bi-functional
electrocatalytic activity, e.g., lower difference in potential between
the ORR at −3 mA cm<sup>–2</sup> and OER at 5 mA cm<sup>–2</sup> (Δ<i>E</i>). Therefore, this work
shows the possibility to adjust bi-functional activity through a simple
process. This correlation may also extend to other perovskite oxide
systems
Palladium-Catalyzed Direct C–H Functionalization of Indoles with the Insertion of Sulfur Dioxide: Synthesis of 2‑Sulfonated Indoles
A palladium-catalyzed
direct C–H bond sulfonylation of indoles
with the insertion of sulfur dioxide is achieved through a three-component
reaction of 1-(pyridin-2-yl)Âindoles, DABCO·(SO<sub>2</sub>)<sub>2</sub>, and aryldiazonium tetrafluoroborates under mild conditions.
Diverse 2-sulfonated indoles are generated by using 10 mol % of palladiumÂ(II)
bromide as the catalyst at room temperature. This synthetic approach
is efficient by merging palladium catalysis and insertion of sulfur
dioxide via a radical process. 2-Pyrimidinyl can be used as the directing
group well as for the C–H bond sulfonylation. Additionally,
the directing group can be easily removed
Direct Carbo-Acylation Reactions of 2‑Arylpyridines with α‑Diketones via Pd-Catalyzed C–H Activation and Selective C(sp2)–C(sp2) Cleavage
An efficient carbo-acylation reaction of 2-arylpyridines with α-diketones via Pd-catalyzed C–H bond activation and C–C bond cleavage in the presence of TBHP was developed that generated aryl ketones in good yields. The highly selective formation of aryl ketones was observed when 2-arylpyridines reacted with aromatic/aliphatic α-diketones
Exceptional Mechanical Stability of Highly Porous Zirconium Metal–Organic Framework UiO-66 and Its Important Implications
Metal–organic frameworks (MOFs)
with high porosity usually
exhibit weak mechanical stabilities, in particular, rather low stabilities
against shear stress. This limitation remains one of the bottlenecks
for certain applications of porous MOFs, such as gas storage or separation
that requires dense packing of the MOF powders under mechanical compression
without collapsing the pores. We found that UiO-66, a prototypical
Zr-MOF with high porosity, exhibits unusually high shear stability.
Its minimal shear modulus (<i>G</i><sub>min</sub> = 13.7
GPa) is an order of magnitude higher than those of other benchmark
highly porous MOFs (e.g., MOF-5, ZIF-8, HKUST-1), approaching that
of zeolites. Our analysis clearly shows that the exceptional mechanical
stability of UiO-66 is due to its high framework connections (i.e.,
the high degree of coordination of Zr–O metal centers to the
organic linkers). Our work thus provides important guidelines for
developing new porous MOFs targeting at high mechanical stabilities
Additional file 2: of ReprDB and panDB: minimalist databases with maximal microbial representation
Title of data: 16S RNA data downloaded from HMP and the variable regions sequenced. Description of data: a list of the 57 samples (SRS) downloaded from HMP, and the variable regions sequenced for each sample. (TXT 1 kb
Highly Uniform Platinum Icosahedra Made by Hot Injection-Assisted GRAILS Method
Highly uniform Pt icosahedral nanocrystals
with an edge length
of 8.8 nm were synthesized in nonhydrolytic systems using the hot
injection-assisted GRAILS (gas reducing agent in liquid solution)
method. The results show the key factors for the shape control include
fast nucleation, kinetically controlled growth, and protection from
oxidation by air. The effect of oxygen molecules on the Pt morphology
was experimentally confirmed based on the study of shape evolution
of icosahedral crystals upon exposure to oxygen gas. The Pt icosahedral
catalysts obtained had an area-specific activity of 0.83 mA/cm<sup>2</sup> Pt, four times that of 0.20 mA/cm<sup>2</sup> Pt for typical
Pt/C catalysts, in an oxygen reduction reaction (ORR)
Exceptional Mechanical Stability of Highly Porous Zirconium Metal–Organic Framework UiO-66 and Its Important Implications
Metal–organic frameworks (MOFs)
with high porosity usually
exhibit weak mechanical stabilities, in particular, rather low stabilities
against shear stress. This limitation remains one of the bottlenecks
for certain applications of porous MOFs, such as gas storage or separation
that requires dense packing of the MOF powders under mechanical compression
without collapsing the pores. We found that UiO-66, a prototypical
Zr-MOF with high porosity, exhibits unusually high shear stability.
Its minimal shear modulus (<i>G</i><sub>min</sub> = 13.7
GPa) is an order of magnitude higher than those of other benchmark
highly porous MOFs (e.g., MOF-5, ZIF-8, HKUST-1), approaching that
of zeolites. Our analysis clearly shows that the exceptional mechanical
stability of UiO-66 is due to its high framework connections (i.e.,
the high degree of coordination of Zr–O metal centers to the
organic linkers). Our work thus provides important guidelines for
developing new porous MOFs targeting at high mechanical stabilities
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