A Novel Method for CFD Analysis of a Two-Zone Mixing Model for HCCI Engines

2011 ◽  
Author(s):  
Matthew J. McCuen ◽  
Zongxuan Sun ◽  
Guoming Zhu
Keyword(s):  
Cfd Simulation ◽  
Mixing Model ◽  
Zone Model ◽  
Exhaust Gas ◽  
Hcci Engines ◽  
Novel Method ◽  
Variable Valve ◽  
Energy Conversion Devices ◽  
Start Of Combustion

Increasing need for clean and efficient energy conversion devices in the automotive sector has pushed technologies such as homogeneous charge compression ignition (HCCI) to the forefront of research. While it offers a number of major advantages in terms of efficiency and emissions, HCCI has significant challenges to overcome before it can be used in a production setting. Among those challenges is the need to control the start of combustion, and one method for doing that is to use variable valve timing to utilize hot, residual exhaust gas. Critical to these residual-affected methods is the role of mixing on the thermodynamic state. This work presents a method for validating a control-oriented two-zone mixing model for HCCI using CFD software. A method of discretizing, extracting, and analyzing the results of the CFD simulation is described, and it is compared with the two-zone model. There is strong correlation, but there is also evidence that the two-zone model needs to be further developed to fully capture the dynamics of mixing.

A Multi-Cylinder HCCI Engine Model for Control

2004 ◽  
Author(s):  
Jason S. Souder ◽  
Parag Mehresh ◽  
J. Karl Hedrick ◽  
Robert W. Dibble
Keyword(s):  
Design Process ◽  
Control Design ◽  
The Other ◽  
Variable Valve Timing ◽  
Valve Timing ◽  
Coupling Effects ◽  
Hcci Engine ◽  
Engine Model ◽  
Hcci Engines ◽  
Variable Valve

Homogeneous charge compression ignition (HCCI) engines are a promising engine technology due to their low emissions and high efficiencies. Controlling the combustion timing is one of the significant challenges to practical HCCI engine implementations. In a spark-ignited engine, the combustion timing is controlled by the spark timing. In a Diesel engine, the timing of the direct fuel injection controls the combustion timing. HCCI engines lack such direct in-cylinder mechanisms. Many actuation methods for affecting the combustion timing have been proposed. These include intake air heating, variable valve timing, variable compression ratios, and exhaust throttling. On a multi-cylinder engine, the combustion timing may have to be adjusted on each cylinder independently. However, the cylinders are coupled through the intake and exhaust manifolds. For some of the proposed actuation methods, affecting the combustion timing on one cylinder influences the combustion timing of the other cylinders. In order to implement one of these actuation methods on a multi-cylinder engine, the engine controller must account for the cylinder-to-cylinder coupling effects. A multi-cylinder HCCI engine model for use in the control design process is presented. The model is comprehensive enough to capture the cylinder-to-cylinder coupling effects, yet simple enough for the rapid simulations required by the control design process. Although the model could be used for controller synthesis, the model is most useful as a starting point for generating a reduced-order model, or as a plant model for evaluating potential controllers. Specifically, the model includes the dynamics for affecting the combustion timing through exhaust throttling. The model is readily applicable to many of the other actuation methods, such as variable valve timing. Experimental results validating the model are also presented.

scholarly journals On the influence of delamination on laminated paperboard creasing and folding

2012 ◽  
Vol 370 (1965) ◽  
pp. 1912-1924 ◽  
Author(s):  
Lars A. A. Beex ◽  
Ron H. J. Peerlings
Keyword(s):  
Cohesive Zone ◽  
Mechanical Model ◽  
Cohesive Zone Model ◽  
Packaging Material ◽  
Friction Model ◽  
Zone Model ◽  
General Mechanics ◽  
Single Fold ◽  
Wide Range

Laminated paperboard is used as a packaging material for a wide range of products. During production of the packaging, the fold lines are first defined in a so-called creasing (or scoring) operation in order to obtain uncracked folds. During creasing as well as folding, cracking of the board is to be avoided. A mechanical model for a single fold line has been proposed in a previous study (Beex & Peerlings 2009 Int. J. Solids Struct. 46 , 4192–4207) to investigate the general mechanics of creasing and folding, as well as which precise mechanisms trigger the breaking of the top layer. In the present study, we employ this modelling to study the influence of delamination on creasing and folding. The results reveal the separate role of the cohesive zone model and the friction model in the description of delamination. They also show how the amount of delamination behaviour should be controlled to obtain the desired high folding stiffness without breaking of the top layer.

Implementation of Smart Home System Based on Internet of Things

2013 ◽  
Vol 475-476 ◽  
pp. 1150-1153 ◽  
Author(s):  
Yan Zeng Gao ◽  
Ling Yan Wei
Keyword(s):  
Internet Of Things ◽  
Embedded System ◽  
Smart Home ◽  
Smart Phone ◽  
Cloud Service ◽  
Control Center ◽  
Cloud Server ◽  
Novel Method ◽  
Smart Phone Application

Smart home can apply new internet of things concepts along cloud service technologies. This paper introduces a novel method for smart home system building. The system is driven by use case and it is composed of home control center, zigbee end devices, smart phone applications and cloud server. The home control center is based on arm-linux embedded system, it is the relay of cloud server and home devices. Wireless network of smart home devices was designed according to zigbee. A smart phone application was developed as the role of the user interface.

PUTRACER: A NOVEL METHOD FOR IDENTIFICATION OF CONTINUOUS-DOMAINS IN MULTI-DOMAIN PROTEINS

2013 ◽  
Vol 11 (01) ◽  
pp. 1340012 ◽  
Author(s):  
SEYED SHAHRIAR ARAB ◽  
MOHAMMADBAGHER PARSA GHARAMALEKI ◽  
ZAIDDODINE PASHANDI ◽  
REZVAN MOBASSERI
Keyword(s):  
Protein Structures ◽  
Three Dimensional ◽  
Accessible Surface Area ◽  
Computer Assisted ◽  
Correct Assignment ◽  
Critical Boundary ◽  
Novel Method ◽  
Accessible Surface ◽  
A Chain

Computer assisted assignment of protein domains is considered as an important issue in structural bioinformatics. The exponential increase in the number of known three dimensional protein structures and the significant role of proteins in biology, medicine and pharmacology illustrate the necessity of a reliable method to automatically detect structural domains as protein units. For this aim, we have developed a program based on the accessible surface area (ASA) and the hydrogen bonds energy in protein backbone (HBE). PUTracer (Protein Unit Tracer) is built on the features of a fast top-down approach to cut a chain into its domains (contiguous domains) with minimal change in ASA as well as HBE. Performance of the program was assessed by a comprehensive benchmark dataset of 124 protein chains, which is based on agreement among experts (e.g. CATH, SCOP) and was expanded to include structures with different types of domain combinations. Equal number of domains and at least 90% agreement in critical boundary accuracy were considered as correct assignment conditions. PUTracer assigned domains correctly in 81.45% of protein chains. Although low critical boundary accuracy in 18.55% of protein chains leads to the incorrect assignments, adjusting the scales causes to improve the performance up to 89.5%. We discuss here the success or failure of adjusting the scales with provided evidences. Availability: PUTracer is available at http://bioinf.modares.ac.ir/software/PUTracer/

scholarly journals 195 The Application of Radiomics in Laryngeal Cancer: The Forgotten Cohort

2021 ◽  
Vol 108 (Supplement_6) ◽  
Author(s):  
A Rajgor ◽  
A McQueen ◽  
T Ali ◽  
E Aboagye ◽  
B Obara ◽  
...  
Keyword(s):  
Artificial Intelligence ◽  
Head And Neck ◽  
Laryngeal Cancer ◽  
Prognostic Value ◽  
Head And Neck Cancers ◽  
High Dimensional ◽  
Naked Eye ◽  
Online Databases ◽  
Novel Method

Abstract Background Radiomics is a novel method of extracting data from medical images that is difficult to visualise through the naked eye. This technique transforms digital images that hold information on pathology into high-dimensional-data for analysis. Radiomics has the potential to enhance laryngeal cancer care and to date, has shown promise in various other specialties. Aim The aim of this review is to summarise the applications of this technique to laryngeal cancer and potential future benefits. Method A comprehensive systematic review-informed search of the MEDLINE and EMBASE online databases was undertaken. Keywords ‘laryngeal cancer’ OR ‘larynx’ OR ‘larynx cancer’ OR ‘head and neck cancer’ were combined with ‘radiomic’ OR ‘signature’ OR ‘machine learning’ OR ‘artificial intelligence’. Additional articles were obtained from bibliographies using the ‘snowball method’. Results Seventeen articles were identified that evaluated the role of radiomics in laryngeal cancer. Two studies affirmed the value of radiomics in improving the accuracy of staging, whilst fifteen studies highlighted the potential prognostic value of radiomics in laryngeal cancer. Twelve (of thirteen) studies incorporated an array of different head and neck cancers in the analysis and only one study assessed laryngeal cancer exclusively. Conclusions Literature to date has various limitations including, small and heterogeneous cohorts incorporating patients with head and neck cancers of distinct anatomical subsites and stages. The lack of uniform data on solely laryngeal cancer and radiomics means drawing conclusions is difficult, although these studies have affirmed its value. Further large prospective studies exclusively in laryngeal cancer are required to unlock its true potential.

scholarly journals The Intermingling of State and Private Companies: Analysing Censorship of the 19th National Communist Party Congress on WeChat

2020 ◽  
pp. 1-30
Author(s):  
Lotus Ruan ◽  
Masashi Crete-Nishihata ◽  
Jeffrey Knockel ◽  
Ruohan Xiong ◽  
Jakub Dalek
Keyword(s):  
Communist Party ◽  
Information Control ◽  
Private Companies ◽  
Political Events ◽  
Critical Content ◽  
Novel Method ◽  
The Government ◽  
The Relationship ◽  
Party Congress

Abstract This paper examines the relationship between political events and information control on WeChat through a longitudinal analysis of keyword censorship related to China's 19th National Communist Party Congress (NCPC19). We use a novel method to track censorship on WeChat before, during and after the NCPC19 to probe the following questions. Does censorship change after an event is over? What roles do the government and private companies play in information control in China? Our findings show that the system of information control in China can trigger blunt reactions to political events. In addition to critical content around the Congress and leaders, WeChat also censored neutral and potentially positive references to government policies and ideological concepts. The decision making behind this censorship is a product of the interaction between the government, which influences actions through directives, and the companies, which ultimately implement controls on their platforms. While this system is effective in compelling companies to implement censorship, the intermingling of the state and private companies can lead to outcomes that may not align with government strategies. We call for a deeper understanding of the role of private companies in censorship and a more nuanced assessment of the government's capacity to control social media.

scholarly journals A Novel Method for Notable Reducing Phase Transition Temperature of VO2 Films for Smart Energy Efficient Windows

Nanomaterials ◽  
2019 ◽  
Vol 10 (1) ◽  
pp. 58 ◽  
Author(s):  
Huan Guan ◽  
Dongping Zhang ◽  
Yu Yang ◽  
Yi Liu ◽  
Aihua Zhong ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Carrier Concentration ◽  
Phase Transition Temperature ◽  
Energy Efficient ◽  
Measurement Results ◽  
High Transition ◽  
Novel Method ◽  
Parameters Measurement

Although Vanadium dioxide (VO2) has a potential application value for smart energy efficient windows because of its unique phase transition characteristic, there are still many obstacles that need to be overcome. One challenge is to reduce its high transition temperature (ζc = 68 °C) to near room temperature without causing its phase transition performance degradation. In this paper, a novel method was employed that covered a 3 nm ultra-thin heavy Cr-doped VO2 layer on the pure VO2 films. Compared with the as-grown pure VO2, obviously, phase transition temperature decreasing from 59.5 °C to 48.0 °C was observed. Different from previous doping techniques, almost no phase transition performance weakening occurred. Based on the microstructure and electrical parameters measurement results, the mechanism of ζc reducing was discussed. The upper ultra-thin heavy Cr-doped layer may act as the induced role of phase transition. With temperature increasing, carrier concentration increased from the upper heavy Cr-doped layer to the bottom pure VO2 layer by diffusion, and induced the carrier concentration reach to phase transition critical value from top to bottom gradually. The present method is not only a simpler technique, but also avoids expensive alloy targets.

A comparative study into the effects of pre and post catalyst exhaust gas recirculation on the onset of knock

2020 ◽  
pp. 146808742096229
Author(s):  
Dominic Parsons ◽  
Simon Orchard ◽  
Nick Evans ◽  
Umud Ozturk ◽  
Richard Burke ◽  
...  
Keyword(s):  
Exhaust Gas Recirculation ◽  
Exhaust Gas ◽  
Engine Combustion ◽  
Low Load ◽  
Fine Control ◽  
Novel Method ◽  
Gdi Engine ◽  
Stochastic Phenomena ◽  
Gas Recirculation ◽  
Onset Angle

Exhaust gas recirculation (EGR) is proven as a valuable technology for controlling knock whilst maintaining lambda one operation, and is also capable of providing efficiency gains at low load. Despite this few studies in the literature address the question of EGR composition effects, namely whether the EGR gas is sourced from before or after the catalyst, and this remains an area which is often overlooked whilst investigating EGR performance. This paper demonstrates a novel method combining experiment air-path emulation and in-depth data processes to compare the effect of EGR catalysis on the angle of knock onset in a 1L GDI engine. Since initial temperature and pressure have a significant impact on knocking behaviour, an artificial boosting rig replaced the turbomachinery. This enabled fine control over the engine boundary conditions to ensure parity between the catalysed and un-catalysed cases. To overcome the difficulty of comparing stochastic phenomena in an inherently variable dataset, a pairing method was combined with Shahlari and Ghandhi’s angle of knock onset determination method to assess the effects of EGR composition on knock onset for EGR rates ranging from 9% to 18%. The air path emulation system stabilised the engine combustion to provide a suitably rich dataset for analysing knock using the pairing method. Catalysed EGR improved the mean knock onset angle by 0.55 CAD, but due to the inherent variability in cylinder pressure data this only equated to a 58.3% chance of a later knock onset angle for catalysed EGR in any given pair of comparative cycles.

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