Nel i polimeri furono distinti da Wallace Carothers in polimeri di addizione e polimeri di condensazionea seconda che la reazione di polimerizzazione produca rispettivamente solo il polimero o anche una specie a basso peso molecolare chiamata "condensato". I poliuretani polimeri prodotti a partire da un diisocianato e un diolo sono ad esempio polimeri di addizione. I polimeri ottenuti per polimerizzazione a stadi sono in genere polimeri di condensazione, mentre i polimeri ottenuti per polimerizzazione a catena sono in genere polimeri di addizione.
La tabella seguente mette in risalto le principali differenze che intercorrono tra la polimerizzazione a catena e polimerizzazione a stadi. A livello industriale, esistono 4 differenti metodi di produzione dei polimeri per addizione, che si differenziano a seconda delle fasi coinvolte nel processo: . Ha come vantaggi l'assenza di solvente che comporta dei costi, produzione di sostanze inquinanti e deve essere successivamente recuperatoed il fatto che la polimerizzazione avviene in situdirettamente nello stampo vantaggioso soprattutto per il PMMA.
Per evitare fenomeni di autoaccelerazione si utilizzano trasferitori di catena. Si frammenta il sistema in massa formando perle di qualche mm di diametro. Ogni particella ha comportamento cinetico come il processo in massa.
L'iniziatore ed il monomero devono essere insolubili in acqua mezzo disperdentee l'iniziatore deve essere solubile nel monomero. Tutte le polimerizzazioni sterospecifiche es. Ziegler - Natta vengono svolte in un solvente idrocarburico. Come caratteristica, si ha che l'iniziatore ed il monomero devono essere solubili nel solvente polare o apolare.
Questa tecnica permette di ottenere alti PM e alte v p. Altri progetti. Da Wikipedia, l'enciclopedia libera. Selke, John D. Culter, Ruben J. Hernandez, "Plastics packaging: Properties, processing, applications, and regulations"Hanser,p.
Altri progetti Wikizionario Wikimedia Commons. Portale Chimica. Portale Ingegneria. Categorie : Processi chimici industriali Reazioni di polimerizzazione. Menu di navigazione Strumenti personali Accesso non effettuato discussioni contributi registrati entra.
Namespace Voce Discussione. Visite Leggi Modifica Modifica wikitesto Cronologia. Wikimedia Commons. Lo stesso argomento in dettaglio: Polimerizzazione a catena. Lo stesso argomento in dettaglio: Polimerizzazione a stadi.
La concentrazione di monomero decresce nel tempo. La concentrazione di monomero si riduce molto presto.5 \
Si ha una fase iniziale di produzione di specie attivate attivazionepassata la quale avviene l'allungamento delle catene polimeriche propagazioneche non aumentano di numero durante questa seconda fase. Durante la successiva fase di terminazione si ha infine una diminuzione del numero di catene polimeriche.
Tutti i radicali in accrescimento a prescindere dal loro peso molecolare hanno uguale costante cinetica . Lo stesso argomento in dettaglio: Copolimerizzazione.Si definisce per questo una " temperatura di saturazione adiabatica ".
Il contenuto di acqua presente in un terreno comprende i seguenti contributi: . Tuttavia, il fatto che un muro sia bagnato non lo degrada affatto: basti pensare alle pile di ponti e alle banchine di porto romane immerse nell'acqua da secoli e ancora in ottimo stato. Nei muri, sfarinamenti, scagliature, marcimenti, ecc. Sono dette "sub-efflorescenze" - mentre le "efflorescenze" volgarmente ed erroneamente dette "salnitro"che sono i cristalli che si formano all'esterno della superficie.
Non causano danni, possono essere semplicemente spazzolate via. Altri progetti. Da Wikipedia, l'enciclopedia libera. Altri progetti Wikizionario Wikimedia Commons.
Portale Meteorologia. Portale Termodinamica. Categorie : Psicrometria Idrologia Pedologia. Menu di navigazione Strumenti personali Accesso non effettuato discussioni contributi registrati entra. Namespace Voce Discussione. Visite Leggi Modifica Modifica wikitesto Cronologia. Wikimedia Commons.You can get your list of topic models directly in your browser using your own username and API key with the following links. You can also paginate, filter, and order your topic models.
Time Series Last Updated: Friday, 2017-10-27 12:23 A time series model is a supervised learning method to forecast the future values of a field based on its previously observed values.
It is used to analyze time based data when historical patterns can explain the future behavior such as stock prices, sales forecasting, website traffic, production and inventory analysis, weather forecasting, etc. A time series model needs to be trained with time series data, i. BigML implements exponential smoothing to train time series models. Time series data is modeled as a level component and it can optionally include a trend (damped or not damped) and a seasonality components as explained below:Forecast equation Level equation Forecast equation Level equation Trend equation Forecast equation Level equation Damped trend equation Forecast equation Level equation Trend equation Seasonality equation The different components can have variations, e.
As a result of combining the different variations for each component, several models can be trained for a given objective field. Note that BigML excludes certain combinations for numerical stability reasons such as additive errors with multiplicative trends or multiplicative error and trend with additive seasonality. BigML computes four different performance measures to select the best model for a given objective field.
You can create a time series model selecting one or several fields from your dataset to use as objective fields to forecast their future values. You can also list all of your time series. This can be used to change the names of the fields in the time series with respect to the original names in the dataset or to tell BigML that certain fields should be preferred.
Example: 100 name optional String,default is dataset's name The name you want to give to the new time series. The type of the field must be numerical. Non-numeric fields will be ignored, and if not present, the right-most valid field in the dataset will be used. The period needs to be set taking into account the time interval of your instances and the seasonal frequency. For example, for monthly data and annual seasonality, the period should be 12, for daily data and weekly seasonality, the period should be 7.
It can take values from 0 to 60. If the period is set to 1, there is no seasonality. If the period is 0, or not given, BigML will automatically learn the period in your data. The range of successive instances to build the time series.
Multiplicative seasonality models are only available when the objective field has strictly positive values (greater than 0). Example: 2 tags optional Array of Strings A list of strings that help classify and index your time series.
If absent, the first datetime field in the dataset whose values are continuously either decreasing or increasing. If not given, the server will auto-detect the first sequential datetime field in the dataset.
All fields are optional: giving any two among start, end, and interval are enough for a full specification, since the remaining one can always be computed. If you give all three, end is ignored and recomputed using start and interval. After the initial pass through the input data, the value of end will be adjusted to coincide with the last non-missing objective value. If the objective field has missing values at its tail, then this adjusted value will differ from the one specified or computed from start and interval.
If you do not specify an objective field, BigML. Once a time series has been successfully created it will have the following properties.The victory comes just a few days after an impressive 2-1 win over Tottenham at home. Leicester City were the hosts in the recent game against Newcastle and they were able to get a 1-0 win in the game. Our betting tips and predictions anticipate a victory for Leicester City.
Yet, this would not be our pick in the game.
Even though Rafa Benitez and his team are at home, Leicester City are on a strong run of form. Craig Shakespeare has seen his team manage only one away victory in the season, but they have been unbeaten in the last five on the road. Four of those matches have finished as a draw, but Leicester have been able to win the last four games against Newcastle. Our preview would go with a victory for Leicester. Newcastle have suffered a poor run of results due to terrible defending in recent weeks.
The team has conceded at almost 3 goals per game in the last six matches. Leicester have been more pragmatic in their approach at both ends of the pitch after scoring eight and conceding six in the last six league matches.
The matches involving Newcastle have witnessed more than 2. While Leicester City have not seen such a high frequency of high-scoring matches in recent times, these two teams are expected to play out a game with more than 2. Our total goals prediction is for more than 2. The England international has come up with seven goals for the season. Rafa Benitez has seen his team go through an extended period of poor form, and it has resulted in Newcastle dropping to 15th place in the table.
Leicester City are now in the top 10 of the table after some impressive results. See Free TutorialsInstant access means you can start learning right now. See CoursesMaster on-camera and off-camera flash for amazing event photos. See Courses Learn to shoot professional headshots on a budget with small flashes. Learn More Skyrocket your productivity and create stunning photos with Lightroom.
Learn More Learn how theprofessionals get greatevent photos every time. Learn MoreDepth of FieldFlash PhotographyModel ShootPhotoshop Layer BlendingTake Better PhotosColor CorrectionRed Eye RemovalPerspective CorrectionLightroom WorkflowDSLR Focus TipsCanon 580EX II SettingsCanon Speedlite to buy. Canon 430EX vs 430 EX IICanon 320EXCanon Flash Blinking DisplayNikon SB-900Wireless TriggersKodak Zi8 vs Flip UltraHDYongnuo RF-602Phottix StratoLearn the core Photoshop skills every photographer needs.
Master the Photoshop techniques that will take your photos from 'OK' to 'Awesome'. In my own attempt to learn photography, I became frustrated by what I perceived as an "information gap. Seeking it out and separating the gems from the junk simply became a waste of time. Phil Steele - Steele Training Tweet. Online video courses make you an expert.We will also link extensively to our SAT study guides throughout this post to give you more targeted advice by section. That means that the math section is now weighted more heavily on the SAT.
It's now very important to get a strong math score to get a good overall composite score. Also, answers now have four choices instead of five. If you want to read a complete breakdown of differences between the old and new SAT, check out our post on the subject. All questions on the redesigned SAT Reading section are based on passages with set topics.
On the old SAT, the questions often came from these categories but the topics were not predetermined.
There is also more emphasis on defining vocabulary in context, understanding and using evidence, making logical arguments, and using scientific reasoning on the new SAT.
The emphasis is now on defining vocabulary in context. Via College Board's Test Specifications for the Redesigned SAT. For the old SAT, knowing vocabulary was crucial to doing well. So in addition to studying vocabulary words, you should also practice doing advanced reading and test your ability to define tough words based on their context.
Your first place to head for SAT Reading practice is the source: the College Board website. They've posted a number of free new SAT practice tests. Start there to get a sense of what the new SAT Reading section is like. Still have old SAT prep books sitting around. You can use old SAT Critical Reading questions to practice, but focus on the passage-based questions and ignore the sentence-completion questions. ACT Reading section questions will also be helpful, as they are all passage-based and contain vocabulary in context as well as logical progression questions.
Another unlikely but helpful source is ACT Science questions. ACT Science also has you break down charts, graphs, and evidence. If you can do well on ACT Science, you will be able to do well on the new SAT data reasoning questions.
Check out some sample questions over the Law School Admissions Council website. Want a bit more structure for vocabulary in context. One of my favorite tools for learning vocabulary in context is a browser app called ProfessorWord. This article alone has about a dozen SAT vocabulary words, according to ProfessorWord. The writing section is quite different on the new SAT.
There is more emphasis on logic and expression of ideas, higher-level writing skills, and punctuation. This means that there are fewer grammar rules tested in isolation, which in turn means fewer "gotcha" questions on the new SAT Writing section.
However, being aware of writing style, construction, and organization is more important, since you will now be working with longer passages. Start your studying by learning English grammar rules by heart. Then give the SAT's official practice tests a try. In terms of additional practice questions, we recommend you use ACT English practice questions, as these are all passage-based, like the new SAT Writing questions are.
You can also use old SAT Writing multiple-choice questions to test your grammar rule knowledge, but remember to be ready for passages. Finally, the more you read and write, the better you will get at spotting writing organization and style naturally. The essay score is now completely separate from the writing score.
The essay is now 50 minutes long instead of 25.Martha O'Connell, United States Iceland Full Circle, May 2017 We had a wonderful time. William Gossett, United States Exotic Hideaways - Winter, April 2017 We greatly enjoyed the tour and have specifically recommended it to friends already (to see if they want to join us for another one.
Jennifer Brinker, United States Iceland Full Circle, March 2017 I've already recommended Nordic Visitor to two friends. Sharon Addis, United Kingdom Iceland Full Circle - Winter, March 2017 Your company is terrific.
Sandra Elsom, United Kingdom Northern Lights Circle Tour, February 2017 I was just so impressed with everything. Amanda Risner, United States Iceland Winter World, January 2017 Thor was excellent. Utterly perfect Naomi Lane, United Kingdom Icehotel Winter Adventure, December 2016 The overall experience exceeded our expectations and was a truly wonderful experience.
Mary Dawson, United States A New Year's to Remember in Iceland, December 2016 I cannot express enough how much we loved every aspect of this trip. Wendy, United States Golden Circle and South Coast - Winter, December 2016 Thanks so much. We got to have exactly the vacation we wanted, and it was just wonderful. Christina, United States Icelandic Winter Highlights, October 2016 The tour exceeded my expectations.
It was an unforgettable experience to an extraordinarily beautiful country. The tour guide was sincere, knowledgeable and kind. He being a native to Iceland made the experience even more authentic.
The group size was perfect, enabling the guide to personalize the tour even more. It was good to have some personal time in Reykjavik to explore on my own. I felt it a very walkable city, and I felt completely safe exploring on my own.
The locals were always friendly, and willing to help me find my way when I got a little turned around. I've wanted to visit Iceland four about 12 years, and realizing a dream through this tour was more than I could have asked for. Thank you - I'll be returning to Iceland.
Sandy, United States Iceland Winter World, October 2016 Outstanding Tour and the people were wonderful. Hilmar did an outstanding job long distance and this tour was more than I had ever anticipated.
What a beautiful place. Thank you for your dedicated help and follow through. John, United Kingdom South Iceland at Leisure - Winter, October 2016 We had an amazing time in Iceland visiting some incredible places. The tour was well put together, with each day full of interest. We visited many of your recommended places along our route, all of which we enjoyed greatly. Mayur, United States Express Iceland, October 2016 You were absolutely amazing from the beginning till the end.
Tay Wei Ting, Singapore Exotic Hideaways, September 2016 The little gems along the way were a great touch. Stephanie, Australia Iceland Full Circle, September 2016 All the guesthouses we stayed in were very very comfortable. Margaret and Paul, United Kingdom Iceland Full Circle, September 2016 The day tours were excellent, particularly the ones from Hofn, Isafjordur and Akureyri.
Greg, United States The Golden Triangle of Scandinavia, September 2016 Sofia was very, very helpful. Eric, United States Majestic Highlights of Norway, September 2016 Thank you Nordic Visitor for helping us to create a honeymoon trip to Norway that we'll never forget.
Petra did an amazing job of lining up incredible sights and accommodations during our 11 day trip- thank you for all of your expertise and assistance. Glyn and Bozena, United Kingdom Romance Around Iceland, September 2016 Our whole honeymoon was amazing from start to finish and we would just like to thank Sigfus for putting all the hard work in to making it so special for us.She is a wonderful addition to your staff.
Your itinerary, maps, suggestions, etc. Having a GPS also made finding everything, including hotels, very simple. Everything about the tour was perfect. It was great arriving at the airport and having someone their with everything we needed. Our overall experiences were great. Everything was well organized. When ever anyone in our group had a question or concern our email was answered quickly. We were very impressed with our personal itinerary and all the materials provided upon arrival (especially the map with our highlighted route and personal notes).
We were delighted with our accommodations, especially on the DFDS overnight ship from Copenhagen to Oslo. It made such a difference and the buffet was superb. Sofia really looked after us, the emails were detailed and friendly and she just made our holiday a pleasure. Every night we asked ourselves "What does Sofia have for us tonight. We were very satisfied with our tour (8 days around Iceland). The group was a good size (16).
Our tour guide, Alfred, was great and very knowledgeable. All of the restaurants and hotels were acceptable. We got to see all of the major highlights and a few hidden things we wouldn't have found on our own. It was nice to have someone else drive and take care of logistics.
We have just returned from a week's self touring holiday of Reykjavik and Southern Iceland, arranged through Nordic Visitor.
From the moment I first contacted the company I knew I had chosen wisely. Their agent, Helga, was efficient, courteous, prompt with responses and very patient as we tweaked our trip. Her suggestions gave us a custom-made itinerary which took us to the best that Southern Iceland had to offer.
After 2 nights in Reykjavik, we stayed at different hotels every night and they were all great. Granted a few didn't look much from the outside, but inside they were brilliant and we had the best rooms they had to offer.
Our mid-way stop was at the Fosshotel Vatnajokull, near Hofn, and the view from the window was of three glaciers - awesome. If you are thinking of a holiday in Iceland then use Nordic Visitor and always ask for Helga - she was brilliant. We've recently returned from holiday in Iceland. I booked us on the Iceland Full Circle self guided tour through Nordic Visitor.
Hilmar was absolutely fantastic to deal with. He was very patient with me as I tried to work through dates and added excursions and always provided quick, informative responses.
The package we received upon arrival was well put together and allowed us to navigate around the country with confidence. Everything had been considered and taken care of. The accommodations were fantastic. We had a self-created situation when we arrived at the airport. Hilmar rang the hotel later in the day to make certain we were settled in with no more issues.
He also called in advance when a glacier tour was cancelled due to a storm. Iceland can be a little intimidating.