I am a total newbie to rfid-tech. Well, i know the basics, but i guess asking this here might be cheaper than buy something to see it doesent work :-).
I'm wondering if any rfid day-to-day cards like banking, time- and/or accesscontrol, transportation etc. are uhf-cards and able to communicate on a long(er) distance (meters instead of centimeters)?
I'd like to count people based on rfid-mesurments, the antenna would be at the entrance of a room (and yes, im aware that one could own more than one :))
Thank you in advance
Chris
Most day to day cards are not UHF-based (yet). They typically would be HF RFID, providing only short reading distances. If you would look for UHF labels, those are mainly used in apparel retail and vehicle identification use cases. Here the long reading distance is a requirement. UHF RFID is just a more recent and newer technology compared to HF, and not that common yet.
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I am researching a problem that is pretty unique.
Imagine a roadside assistance company that wants to dynamically route its vehicles. Hence for each packet of new incidents wants to create routes that will satisfy them, according to some constraints (time constraints, road accessibility, vehicle - incident matching).
The company has an heterogeneous fleet of vehicle (motorbikes for easy cases, up to tow trucks for the hard cases) and each incident states it's uniqueness (we know if it wants just fuel, or needs towing).
There is no depot, only the vehicles roaming on the streets.
The objective is to dynamically create routes on the way, having in mind the minimization of time and the total traveled distance.
Have you ever met such a problem? Do you have any idea in which VRP variant it belongs?
I have seen two previous questions but unfortunately they don't fit with my problem.
The respected optaplanner - VRP but with no depot and Does optaplanner out of box support VRP with multiple trips and no depot, which are both open VRPs.
Unfortunately I don't have code right now, as I am still modelling the way I will approach this problem.
I am really sorry for creating a suggestion question and not a real one.
Thank you so much in advance.
It's a rich dynamic/realtime vehicle routing problem. You won't find an exact name for your problem, as when VRPs get too complex they don't fit inside any of the standard categories.
It's clearly a dynamic/realtime problem (the terms are used interchangeably) as you would typically only find out about roadside breakdowns at short notice.
Sometimes you're servicing a broken down car, which would be a single stop (so a vehicle routing problem). Sometimes you're towing a car, which would be a pick-up delivery problem. So you have a mix of both together.
You would want to get to the broken down vehicles ASAP and some would need fixing sooner than others (think a car broken down in a dangerous position on a motorway). You would therefore need soft time windows so you can penalise lateness instead of the standard hard time windows supported in most VRP formulations.
Also for you to be able to scale to larger problems, you need an incremental optimiser that can restart from the previous (possibly now infeasible) solution when new jobs are added, vehicle positions are changed etc. This isn't supported out of the box in the open source solvers I know of.
We developed a commercial engine which does the above. We started off using the jsprit library, which supports mixing single stop and pickup delivery problems together. We later had to replace jsprit due to the amount of code we had to override to get it running happily for realtime problems, however jsprit may still prove a useful starting point for you. We discuss some of the early technical obstacles we had to overcome in getting jsprit to handle realtime problems in this white paper.
I coded a program in which people rate different products. Per rating people get a bonus point. The more bonus points people get the more reputation they get. But my issue that people sometimes give ratings not to rate but just to earn bonus points. Is there a mathematical solution to identify fake raters?
Absolutely. Search for "shilling recommender systems" in Google Scholar or elsewhere. There has been a decent amount of scholarly work identifying bad actors in recommender systems. Generally there's a focus on preventing robot actions (which doesn't seem to be your concern) as well as finding humans who rate differently than the norm (i.e., rating distributions, time-of-rating distributions).
https://scholar.google.com/scholar?hl=en&q=shilling+recommender+systems
my graduate project is about Smart Attendance System for University using RFID.
What if one student have multiple cards (cheating) and he want to attend his friend as well? The situation here my system will not understand the human adulteration and it will attend the detected RFID Tags by the reader and the result is it will attend both students and it will store them in the database.
I am facing this problem from begging and it is a huge glitch in my system.
I need a solution or any idea for this problem and it can be implemented in the code or in the real live to identify the humans.
There are a few ways you could do this depending upon your dedication, the exact tech available to you, and the consistency of the environment you are working with. Here are the first two that come to mind:
1) Create a grid of reader antennae on the ceiling of your room and use signal response times to the three nearest readers to get a decent level of confidence as to where the student tag is. If two tags register as being too close, display the associated names for the professor to call out and confirm presence. This solution will be highly dependent upon the precision of your equipment and stability of temperature/humidity in the room (and possibly other things like liquid and metal presence).
2) Similar to the first solution, but a little different. Some readers and tags (Impinj R2000 and Indy Readers, Impinj Monza 5+ for sure, maybe others aswell) have the ability to report a response time and a phase angle associated with the signal received from an interrogated tag. Using a set up similar to the first, you can get a much higher level of reliability and precision if you use this method.
Your software could randomly pick a few names of attending people, so that the professor can ask them to identify themselves. This will not eliminate the possibility of cheating, but increase the risk of beeing caught.
Other idea: count the number of attendiees (either by the prof or by camera + SW) and compare that to the number of RfID tags visible.
There is no solution for this RFID limitation.
But if you could then you can use Biometric(fingerprint) recognition facility with RFID card. With this in your system you have to:
Integrate biometric scanner with your RFID reader
Store biometric data in your card
and while making attendance :
Read UID
Scan biometric by student
Match scanned biometric with your stored biometric(in the card :
step 2)
Make attendance (present if biometric matched, absent if no match)
Well, We all have that glitch, and you can do nothing about it, but with the help of a camera system, i think it would minimise this glitch.
why use a camera system and not a biometric fingerprint system? lets re-phrase the question, why use RFID if there is biometric fingerprint system ? ;)
what is ideal to use, is an RFID middleware that handle the tag reading.
once the reader detects a tag, the middleware simply call the security camera system and request for a snapshot, and store it in the db. I'm using an RFID middleware called Envoy.
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Summary
We are start up and we provide software development services. We develop windows, web, services and mobile applications. We were aware of agile and we are scrum certified developers . We do user story based estimation and task planning. No issues.
Issue
We are approached by many small customers. Customers says very high level features or few words about the concept of their dream project. They asks for Effort Estimation and Cost Estimation. Mostly they are interested in Cost.
For each customer we did create the user stories and estimated the user stories and based on story points, we estimated the effort in days and we convert the days to the cost based on hourly rate. We involve the team of 3 or 4 people and get the estimation done. We spend at least 20 to 30 hours of team total time for estimation. (Team of 4 discussing for 5-6 hours)
The problem is that many customers would never turn back. We do not want to spend 20-30 hours of team effort. We don't want to use the exact user story estimation that we follow for contract signed project.
Question
What could be done in order to provide approximate estimate for small customers with small business?
I don't know there is a solution, other than to find 'better' customers. It sounds like you're doing it right to me. Non-technical customers often want you to spend 30min on the phone with them and then give them a price for the whole thing, so it's good you take the time over it properly. However then you often waste your time.
Maybe you need to say 'no' to customers who you don't think are serious. Or charge for the time spent doing highly skilled estimation work.
By 'better' customers I mean bigger companies, who are more experienced with software (and also probably have bigger budgets). The downside is more paperwork - you are much more 'free' dealing with small firms but also more at risk.
You don't have to stick to a fixed-price contract, for requirements that are vague you should look at doing time and materials.
Basically you need to spread the risk of the cost of overrun between you and the client.
A hybrid option might be to do some T&M proof of concept work then fixed price for the rest when you understand it better.
Alternatively, if you client has a pot of money then use your agile strengths to work with the customer to incrementally deliver functionality until they run out of money.
"We do not want to spend 20-30 hours of team effort."
Then don't.
If your estimating method is too costly, stop doing it.
"Customers ... are interested in Cost."
Then get them a cost more quickly. Do less work. Don't use a team of 3-4 for 20-30 hours. Have one person do it quickly.
One person can create a spreadsheet with stories, story points, priority, hours and cost. That's the project backlog for Scrum. That's the estimate. That's enough to start a conversation. It's not a fixed-price estimate.
A simple spreadsheet with stories, story points, price and priority is all you need. Then you can work with the customer to adjust priorities to determine how many of those stories they can actually afford to buy.
If they want a fixed price, you simply need to review each story summary to see if the points are right. You already have the spreadsheet, and the priorities, and the formula to compute price.
The unfortunate short answer is you are going to have to significantly reduce your estimation costs. The only way to do that is to reduce the number of people to one and use a formula approach.
Take a best guess. Put reasonable assumptions in the contract. If you do a decent job, some will be a little high, some will be a little low and it will average out in the end. If you are off by too much, track changes within the project and charge for them. The key will be in the assumptions placed in the contract, usually in the form of a statement of work.
This is normal business, from small projects to enterprise projects. Just a matter of scale. It doesn't have to be done this way, but it often is.
This reminds me of the challenge between time, money, people and overall quality. Some people can see this easily and others may struggle with the idea. Part of the key point here is to understand is what kind of expectations do you want to set and what kind of leeway do you have with the customer. For example, how are bugs in the software or overall support factored into the project.
You may want to consider how much work do you want to do upfront and on what kind of scale are you spending the 20-30 hours estimating a project. Comparing the cost of that much time spent generating an estimate, which # $40/hour is $800-1,200 by the way, to what the revenue from the project would be is something to consider. If the entire project is $400, then was it worth spending twice that coming up with an estimate? On the flip side, for million dollar projects, it may well make sense to spend that kind of money.
My suggestion would be to see if there is a cookie-cutter approach that could be taken for their projects so that there isn't as much variability to the projects if that is possible.
Theres two sides of estimation, first creating the initial 'ball park' figure this should be done relatively quickly, it should be emphasised its a ball park figure and its the start of your conversation with your customer, its not a contract. Second you do your more detailed team based estimation.
This is how this consulting company does it - Ball Park Estimating
Create a template spreadsheet with times and costs for typical pieces of work, look at the initial requirement and update your template. Start the conversation with this is the ball park but we will need to work together to confirm a final price and get a more accurate estimate. This more accurate estimation process will take x hours and cost x dollars.
Many websites today (including stackoverflow) and games allow people to perform voting, give feedback, enable additional features etc, according to a score: eg. reputation, or MMORPG credits.
As a programmer that will probably need to implement a community based website in the near future, I am interested in knowing about the existence of basic algorithms and decisions to be made so that everything is balanced. For example, the fact that one vote up grants 10 reputations and one down grants -2 was arbitrary or properly weighted ? How to decide the price of a given item and the rewards in a MMORPG, so that everything is balanced? I guess that WoW designers relied on their experience, but I am also sure that this experience can be found somewhere written down. Although this is a social problem, the pricing of a given feature and the reward for a given task are technical/mathematical ones, as you need to give a value to each feature according to some mathematical criteria (although not easy to devise, I guess)
Of course, this question could bring us far in terms of theory of economics, but I am sort of hoping that there are well defined and known simplified patterns and rules for this issue. I just don't know the keywords to query for.
Probably the most important thing to point out here is that this is a social problem not a technical one.
By that I mean that you could use the exact same system as SO on an MMORPG and it would flop or have really undesirable side effects. Whether a system works or not depends on the community you drop it into and the intended purpose. It can also depend on some luck whether people latch onto it or not. You may get early negative behaviour that sets the tone for future negativity and discourages positive involvement. Or it could go completely the other way.
There is no magic formula that made the vote/rep weighting what it is on SO other than long discussions about how to encourage certain behaviour and then some testing and fine-tuning. For example, a downvote costs 1 rep and is -2 rep to the recipient. The guiding principle was that downvotes should cost. After that, it was trial by error.
You might want to read The Value of Downvoting, or, How Hacker News Gets It Wrong and Vote Fraud for some of Jeff's and Joel's thoughts on that subject. Joel's Tech Talk on Stackoverflow at Google is also enlightening.
Voting is actually a very difficult problem. There are so many models of voting, and they all produce different results. For example, choosing your one favorite candidate versus ranking candidates produces a different result. Choosing your LEAST favorite candidate produces a different result. Organizing choices into good/bad produces different results.
Balancing then becomes something that can be done by asking the community. It's very difficult to balance games of that magnitude, simply because even your most exhaustive tests wont cover all of the cases. Having a properly established forum where users can give their opinions as well as having testers who watch out for balancing issues is probably the best way to go.
Oh, and if you want an abstract about the voting problem I mentioned, it's here:
http://www.cs.rochester.edu/~lane/computational-politics.html