Emre Can Kara

on thermal comfort

eckara — Tue, 06 Nov 2012 02:49:30 +0000

I have been trying to get my mind around what to do next to get myself closer to a possible proposal defense early next year.
Considering the amount of work I have already done on engaging relatively small thermostatically controlled loads (TCLs) to the power grid as ancillary service providers (which is still preliminary although with some promising results), I guess the biggest question in my mind threatening the deadline of the PhD proposal was “How to extend the scope of the work to larger TCLs, or to be more specific to HVAC systems?”.
Trying to mess around with the HVAC system of a commercial building has some obvious challenges. To begin with: the occupants. You have to make sure that during the control period the climate conditions within the building stay as comfortable. And even from life experience, I think most of you would know that satisfying everybodys needs is a difficult task. I guess ever since I have seen this picture in B.W. Olesen’s PhD thesis, this is the image of occupants enjoying their work in their office’s comfortable environment in my mind. I have to admit it might have some motivational effect on PhD students working on thermal comfort.

: Comparison between different comfort conditions for different age, clothing and activity (Source: B.H. Olesen’s PhD thesis)

Other than the end-user comfort, HVAC systems are much more complicated than a regular electric water heater or a refrigerator where the inside environment is well seperated from the outside. For small TCLs one can think of some disturbances to their regular working cycles such as door openings/ defrost cylces for a refrigerator. However for the HVAC, these disturbances can vary from frequent setpoint adjusment to existence of natural ventilation. Fault detection and diagnosis in HVAC systems are most of the times a hassle. If you ask a building operator/manager “why did he turn off the alarm system of the BMS” he would probably start talking about his headaches due to too many false positives and also will start explaining “how things are managable by only considering occupant complaints.”
Right, so this is where you really want to shift research topics, or replace all the human beings with cyborgs incapable of complaining regarding the inside climate/ do not need an HVAC system at all.. etc.

Leaving “comfort tests under different clothing conditions” and “cyborg occupied buildings” aside and going back to the research problem in my hands and possible answers coming from some really intelligent people, I think investigating the behavior of Variable Fan Drives available in most of the HVAC systems seems a reasonable approach for frequency regulation for the grid.
In addition I am investigating some cool tools that can be useful while simulating a grid formed by a population of different types of loads.

A couple of links for the interested reader: Gridlab-d, Paper1, Paper2

Filed under: Research

uçak notları/ scribbles in a plane

eckara — Tue, 06 Nov 2012 02:39:30 +0000

Uzanıp her yeni günü tuttuğumda..

Ellerimden kayıyor zaman…

Ve sana mahkum kalıyor saatlerim…

Kelimelerimin yolu aklımdan geçmiyor…

Yoruluyor kalbim..

Uyurken titreyen ellerin..

Değişen nefesin..

Korkutuyor beni..

Samandan bir korkuluk gibi kalıyorum olduğum yerde…

Aşkın karanlığına karşı…

Boğazıma kadar aşkın içinde…

…

Gündüzün peşi sıra gelen saatlerden..

Yeniliğin bitmesinden…

Sarkaca dönüsebilen günlerin tek düzeliğinden…

Hayatın ta kendisinden..

Gençliğimden..

Değişen duygularımdan…

Kırdığım kalplerden…

Sensizlikten…

Korkuyorum…

English version:

every time I reach and hold a new day

the time slips through my hands..

time is a stone-cold convict,

sentenced to you..

the pathway to my words; dismal..

my heart; bushed..

and you; asleep.. subtle..

your hands quiver..

your whiff turns into a deep sigh..

and I’m petrified..

steady and obstinate as a scarecrow..

against the shade of love..

and in love…

…

I’m petrified of the hours that chases the dawn..

of a dormant routine,

of prosaic days,

of my youth,

of my unstable feelings,

of all the hearts I have broken unwillingly,

and of loosing you…

I’m petrified…

Her sabah gökyüzünün farklı bir ezgisine uyanıp,

Hızlıca güne karışmak istiyorsan…

Ya da yanında derinleşen nefese kaptırıyorsan kendini..

Bir kadında sabah uykusunun tadını bulduysan…

Zamanının kıymetiyle yerli yersiz yere düşüp…

Aynı hızla yerinden kalkabiliyorsan…

Akdeniz bile onun gibi kokuyorsa sana şimdi…

Vücüdun ve ruhun yersiz çarpışıyorsa…

Dünü ve yarını bir kenara bırakabiliyorsan yanında…

Hayat birlikte izlenilen bir manzaraysa onunla…

Sessizlikler paylaşılıp,

Nedensiz bir gülümsemeyle bitiyorsa…

Her yolculukla onun adı kafiyeleniyorsa..

Her yeni günle gelen gün batımının korkusu dağılıyorsa paylaşılan akşamlarda..

…

Tek duzeliğin penceresinden çıkıp giden hayatına son defa bak…

Bundan sonra hayat daha güzel olacak..

English version:

waking up to a different melody from the sky,

if every day hastily invites you to get lost in it…

…

If you uneasily get caught on a deep sigh of a woman..

or barely discovered the shared ecstasy of morning sleeps..

if the fear of the dusk after each dawn dissolves into shared evenings..

…

if you can fall down unbefitting with the value of time..

and get back up briskly, in no time..

…

If the Mediterranean smells to you of her

and, your body battles with a constant fervor..

If yesterday and tomorrow sets a sail

and, life turns into a view, enjoyed par deux..

if the silence can be shared till a laughter

and her name rhymes with each adventure..

…

Take a last look at your past life..

Like a bird just got loose from the chain of prosiness..

Future will be blithe…

23:57

Şikago-Tokyo Uçağı / Chicago-Tokyo

Kasım 5 / November 5

Filed under: Blog, Poetry

Bir Dost.

eckara — Tue, 04 Sep 2012 03:56:57 +0000

Onunla dakikalar sonsuz..

Saatler ucari…

Bir dostum vardi…

Gecirdigimiz zamanin paydasiydi, ortak hayallerimiz…

Ve hic bitmek bilmezdi birbirimize soyleyemediklerimiz…

…

Hic bitmek bilmedi..

Filed under: Blog, Poetry

They Came

eckara — Tue, 13 Dec 2011 03:38:53 +0000

dressed up as “friends,”
came countless times, my enemies,
trampling the primeval soil.
And the soil never blended with their heel.
They brought
The Wise One, the Founder, and the
Geometer,
Bibles of letters and numbers,
every kind of Submission and Power,
to sway over the primeval light.
And the light never blended with their roof.
Not even a bee was fooled into beginning the
golden game,
not even a Zephyr into swelling the white aprons.
On the peaks, in the valleys, in the ports
they raised and founded
mighty towers and villas,
floating timbers and other vessels;
and the Laws decreeing the pursuit of profit
they applied to the primeval measure.
And the measure never blended with their
thinking.
Not even a footprint of a god left a man on
their soul,
not even a fairy’s glance tried to rob them of
their speech.
They came
dressed up as “friends,”
came countless times, my enemies,
bearing the primeval gifts.
And their gifts were nothing else
but iron and fire only.
To the open expecting fingers
only weapons and iron and fire.
Only weapons and iron and fire.

Filed under: Blog, Poetry

Je vais te dire un grand secret

eckara — Thu, 01 Dec 2011 08:20:06 +0000

Je vais te dire un grand secret Le temps c’est toi
Le temps est femme Il a
Besoin qu’on le courtise et qu’on s’asseye
A ses pieds le temps comme une robe à défaire
Le temps comme une chevelure sans fin
Peignée
Un miroir que le souffle embue et désembue
Le temps c’est toi qui dors à l’aube où je m’éveille
C’est toi comme un couteau traversant mon gosier
Oh que ne puis-je dire ce tourment du temps qui ne passe point
Ce tourment du temps arrêté comme le sang dans les vaisseaux bleus
Et c’est bien pire que le désir interminablement non satisfait
Que cette soif de l’oeil quand tu marches dans la pièce
Et je sais qu’il ne faut pas rompre l’enchantement
Bien pire que de te sentir étrangère
Fuyante
La tête ailleurs et le coeur dans un autre siècle déja
Mon Dieu que les mots sont lourds Il s’agit bien de cela
Mon amour au delà du plaisir mon amour hors de portée aujourd’hui de l’atteinte
Toi qui bats à ma tempe horloge
Et si tu ne respires pas j’étouffe
Et sur ma chair hésite et se pose ton pas
Je vais te dire un grand secret Toute parole
A ma lèvre est une pauvresse qui mendie
Une misère pour tes mains une chose qui noircit sous ton regard
Et c’est pourquoi je dis si souvent que je t’aime
Faute d’un cristal assez clair d’une phrase que tu mettrais à ton cou
Ne t’offense pas de mon parler vulgaire Il est
L’eau simple qui fait ce bruit désagréable dans le feu
Je vais te dire un grand secret Je ne sais pas
Parler du temps qui te ressemble
Je ne sais pas parler de toi je fais semblant
Comme ceux très longtemps sur le quai d’une gare
Qui agitent la main après que les trains sont partis
Et le poignet s’éteint du poids nouveau des larmes
Je vais te dire un grand secret J’ai peur de toi
Peur de ce qui t’accompagne au soir vers les fenêtres
Des gestes que tu fais des mots qu’on ne dit pas
J’ai peur du temps rapide et lent j’ai peur de toi
Je vais te dire un grand secret Ferme les portes
Il est plus facile de mourir que d’aimer
C’est pourquoi je me donne le mal de vivre
Mon amour
Louis Aragon
(Les Yeux d’Elsa : extrait)

I’m going to tell you a great secret You are time
Time is a woman It needs
To be fawned over and bowed down to
Time like a dress to be undone
Time like endless tresses
Combed
A mirror misted and demisted by breath
You are time asleep at dawn when I rise
You’re time like a knife across my gullet
O how I am unable to tell this torment of time unpassing
This torment of time halted like blood in blue vessels
Far worse than desire forever unmet
Than the thirst of the eye when you walk into the room
And my knowing not to break the spell
Far worse than feeling you a stranger
Fleeing
Your mind elsewhere and your heart already in a different century
My God how words are heavy That’s what it’s all about then
My love beyond pleasure my love out of reach today unattained
You swat at my clock temples
And if you fail to breathe I suffocate
And on my flesh your step waits and comes to rest

I’m going to tell you a great secret Every word
On my lips is stricken with poverty, begging
A trifle for your hands something glowing black below your stare
And this is why I say so often that I love you
For lack of a crystal clear enough of a phrase you’d place around your neck
Don’t mind the baseness of my language It is
Plain water making that awful noise in the fire

I’m going to tell you a great secret I don’t know how
To speak of the time you seem to be
I don’t know how to speak of you I make believe
Like those who remain so long on the platform in the station
Waving their hands after the trains have left
The wrist fading out under the new weight of tears

I’m going to tell you a great secret I fear you
Fear what goes with you to the window in the evening
The gestures you make with unsaid words
I fear time rapid and slow I fear you
I’m going to tell you a great secret Close the doors
It’s easier to die than to love
That’s why I take such pains to go on living
My love

—Translated from the French by Christophe Brunski
(from Elsa, 1959)

Filed under: Poetry

Modeling Uncertainties in Aggregated Thermostatically Controlled Loads Using a State Queueing Model

eckara — Thu, 24 Nov 2011 05:56:55 +0000

Authors: Ning Lu, Member, IEEE, David P. Chassin, Member, IEEE, and Steve E. Widergren, Senior Member, IEEE

Discussion

I like their idea of adjusting the transition matrix -P in their case- to account for the disturbances in their model. The time dependency of the probabilities might be an issue when dealing with a load following simulation.
Since their state adjusted transition matrix includes a certain probability value for an appliance to change its state to the previous one due to disturbances, the expectancy of an appliance to change multiple states decreases exponentially in time.

Benefits and thoughts on my research:

Can we arrange the A- our transition- matrix so that we include the disturbances due to consumer behavior for the refrigerator? Think about what would happen if you have water heaters in your system. The requirement for identifying different TCLs can be motivated by mentioning different characteristics in terms of demand management service needed.
A steady state case will be highly likely for water heaters when there is no demand especially during night time. This paper mentions up to 10 hours of off cycle. Without shifting the temperature upper bound to a higher value turning on is not possible. Heat loss takes too much time.
If thats the case suggesting TCls for 24h other than refrigerators or hvac does not make sense. The disturbance levels on HVAC systems for residential buildings will be smaller during night time. The offices most probably have a lower set point with less disturbance=empty building.

Can we end up with an upper boundary of the interior temperature/water temperature/?
Again contextual information motivated here. How much can i shift my set point up? One easy way to do that is maybe to look at the power and keep building up your model.?

Can we relatively capture the information by looking at power?

It is high likely that we can predict the current state of the appliance relative to its temperature dead bands. Is it possible to say a typical water heater can at most have X times it’s lower/upper dead band?

Notes to self:
Does having same number of bins for each state includes the assumption of both states will take similar time during a regular operation cycle in your model?

Filed under: Research

on my very recent and daily suffering

eckara — Wed, 23 Nov 2011 20:01:54 +0000

Ok. Fair enough. I have been working on a simulation based on a Model Predictive Controller and it took way more than I was expecting (-yes! I am still struggling-). Apparently reading a very well written text book on MPC and doing fair amount of feedback control systems class assignments are not enough to tackle a simulation… Why is that? I will discuss my mental health and my intellectual capabilities in an other post, preferably sometime I can zoom out from my current tasks… (Yes, I had nightmares involving Model Predictive Control)

I am so involved in this piece of code that I always think the only way to implement it is exactly how I did it. Many times I find myself focusing on a little tiny detail too much and think on it exhaustively to a point I feel completely lost. A very useful and more elegant way to tackle this problem is writing about what you are doing and why you are doing that. As most of my friends and professors here say: “as if you are trying to explain it to your grandmother”. At this very moment, you might think that we as CMU’ers are crazy people. Describing the code you have written in C/Matlab to validate it as a solution to a research problem is a hard task by itself and discussing it with your grandmother?… Imagine the scene… That is hilarious indeed…

I have been a very disorganized person. I was one of those people that said: ”I live in my own jungle, it might look disastrous and scatty but I know where any item is”. I still can agree with such an approach so to say. Believe me I used to know the location of what I am using already or what I might need in near future. The problem with it is: I cannot track it down to a year even. And trust me by observing other PhD students, reading/listening past stories about challenging research tasks one can realize that at some point “you will need to go back”.

So this is the main reason that this time I am sure I will try to keep this blog updated. Whenever I get lost or I need to develop a general picture of what I am doing and why I am doing it, I hope this blog will motivate me to do so…

Filed under: Research

The Bread of the People.

eckara — Wed, 26 Oct 2011 12:34:00 +0000

Justice is the bread of the people
Sometimes is plentiful, sometimes it is scarce
Sometimes it tastes good, sometimes it tastes bad.
When the bread is scarce, there is hunger.
When the bread is bad, there is discontent.

Throw away the bad justice
Baked without love, kneaded without knowledge!
Justice without flavour, with a grey crust
The stale justice which comes too late!

If the bread is good and plentiful
The rest of the meal can be excused.
One cannot have plenty of everything all at once.
Nourished by the bread of justice
The work can be achieved
From which plenty comes.

As daily bread is necessary
So is daily justice.
It is even necessary several times a day.

From morning till night, at work, enjoying oneself.
At work which is an enjoyment.
In hard times and in happy times
The people requires the plentiful, wholesome
Daily bread of justice.

Since the bread of justice, then, is so important
Who, friends, shall bake it?

Who bakes the other bread?

Like the other bread
The bread of justice must be baked
By the people.

Plentiful, wholesome, daily.
Bertolt Brecht

Filed under: Poetry

sincapla dertlesmek..

eckara — Tue, 25 Oct 2011 20:53:00 +0000

dusunuyorum oyleyse varim… calisiyorum oyleyse yokum… zamani geldi yine disardan bakmanin hayata… calismayi rolantiye almanin vakti geldi… yaptiklarini sorgularken birseyler basarmak o kadar zor ki.. calisiyorken “yok” olmak lazim… tartarken calismamak… simdilik tartiyorum tum kararlarimi.. ortamimi… ve bu sincaplar nedendir bilinmez bana babami hatirlatiyor… hareketlerindeki ceviklik… suratlarindaki yeterince muzip ifade… bir o agactan bir o agaca ziplayan, uyudugunu goremedigim, bana ‘calisma’ kokan varliklar diyelim… biri durup onumde bana iki dakika manali bir bakis atiyor sanki… ‘efendi calismadan olmaz’ diyor… sonra yoluna gidiyor…

Filed under: General

vas y venis

eckara — Thu, 06 Oct 2011 07:51:00 +0000

De carrasco a aeroparque y viceversa
vas y venís con libros y bufandas
y encargos y propósitos y besos

tenés gusto a paisito en las mejillas
y una fe contagiosa en el augurio

vas y venís como un péndulo cuerdo
como un comisionista de esperanzas
o como una azafata voluntaria
tan habituada estás a los arribos
y a las partidas un poquito menos

quién iba a imaginar cuando empezábamos
la buena historia hace veintiocho años
que en un apartamento camarote
donde no llega el sol pero vos sí
íbamos a canjear noticia por noticia
sin impaciencia ya como quien suma

y cuando te dormís y yo sigo leyendo
entre cuatro paredes algo ocurre

estás aquí dormida y sin embargo
me siento acompañado como nunca.

M. Benedetti.

Filed under: Poetry